AIO: Boyfriend's daughter took something of mine. I said I wanted it back 2 months ago. I just received the item back because she decided to let it go when her grandparent's bought her something new to apparently' that its place?

Try to make this as short as I can. I'm severely frustrated, and of course, there is a lot more to this situation than I can explain in one post on Reddit.

Note: Please also be kind. If I am in the wrong here, that is fine, I will accept that, but please be kind in your responses. I have been in nothing but abusive AF relationships my entire life and yesterday was a really hard day as it was the birthday of the person I loved the absolute most in this world. I have not been okay without my dad...I don't know if I'm overreacting or if the way I think or would do things [immediately if roles were reversed here] is just some weird messed up thing my brain does. Please, be kind. I am open to being wrong if I can be told why this is a ridiculous thought pattern.

To be clear: I'm not asking for a "stay or leave" answer from the community. What I would like to know is if I'm over reacting (as a human riddled with ADHD, depression, panic and anxiety) this is a big deal to me. I want to know specifically, neurodivergent, neurotypical, all sides of it, how would you feel about this situation? Am I justified in being upset and feeling incredibly small and disrespected? Or is this what is considered normal, and I need to tell my stupid brain and feelings to just take a chill?

Situation:

My (38f) boyfriend (40m) and I have been together about a year and a half. He has 2 daughters, 13&12, I have 4 children: 2 boys (14&13), and then 2 daughters (5&3).

This also seems to be relevant (though I don't think it is, but it does seem to be what is said or alluded to when there is an issue): boyfriend and ex-wife legally divorced in 2018, making his daughters 4, nearly 5, and 3 at that time. Again, irrelevant to the story, but just so it's out there, my divorce was requested and finalized in 2019 (my boys were the ones that came of that relationship) making them 8&7.

The similarities I see between my oldest and his oldest, and my youngest boy and his youngest, are uncanny. Maybe it's a thing with kids that have siblings. I wouldn't know, as I'm an only child. My eldest son definitely had anger issues thanks to his father. I spent countless years working with him to ensure I didn't release another of my ex-husband into the world to prey on women. Not going to lie, I didn't a pretty damn good job. We don't have the arguments and the fights and the banging fists on the door like we used to when he didn't get his way, because I was firm, but not mean, and when I said no, it stayed that way.

My boyfriend...did not do that. For reference, due to the way his divorce came about, he has custody of his girls, the typical "mom" schedule in regards to custody. His eldest, we can call her B, is...entitled, at minimum. Think Regina George from Mean Girls, but in real life, at home and at school. She has the ability to be a very nice girl...but she most often chooses not to be. This comes out at everyone: her sister, her dad, my children, and in less outward but sneakier parts, me.

She has a mom, I am not in the position nor do I have the desire to attempt to replace her. That is not my role, and I'm perfectly fine with that. If either of his children want me, I'm there, and they can come to me, but I am not actively trying to step in and take the place of "mom". She's here, B is obsessive (and takes on a lot of her mom's negative traits, unfortunately) about her mom, and that's okay.

That said. I mentioned she is quite literally the physical 13 year old embodiment of Regina George. My frustration is growing with what she gets away with (literally everything...my boyfriend's parents are even on board with fulfilling her every desire and whim which absolutely blows my mind, but not the point...). Here is where it has come to a head. The issue is, yes, with her and the entitlement, but my biggest frustration and issue is my boyfriend, and how he has (not) dealt with it.

I brought to our shared home my 8 cube storage organizer, approximately 2 months ago. I was really beat down that night and got it out of my car but not into the house. Next thing I know, it's missing. Umm...okay...?

Walked into B's room to put laundry on her dresser for her to put away and lo and behold, there's my organizer, in her room, with her TV on it. That night, I went to her father, my boyfriend, we can call him C, and asked, "Hey, I was putting stuff away and when I went into B's room, I saw my organizer...what...happened?"

C told him B came and asked him. C tells me he told B, "It isn't mine, it's (H, I'll be H) H's, you have to ask her."

I told C at that point, "Um, she didn't? I brought it here for a reason...it wasn't for B to take without asking?"

C wasn't "adamant" I wouldn't say, and not angry or defensive (he's the most zen asshole on the planet, I am so envious of his ZEN) but more or less he acknowledged that I was not asked. I, being foolish, assumed that would be the end of that and I would receive my organizer back. (For the record, I truly DID have plans to use it.)

Over the past 1.5-2 months, this has been an argument between myself and C. I feel ignored, I feel small, I feel disrespected, and I feel like I just DO NOT matter.

According to C, he told B it was not his item to give and she had to ask me if she could have it. B did not. When I bring this up, about a slew of different things, C always falls back to, "B is mad her mom and I got divorced. If it wasn't you she didn't like, it would be someone else."

Like, idgaf? It IS me, and my children...I truly don't give a damn if it would be like this with anyone else, this is me? "She needs therapy and I can't get her in anywhere." [To be fair, we do live in a small area. Therapy is actually tough to come by but like...telehealth is a thing, and I personally think kids will do better with that anyway, but I digress...]

2 months later, because a magic POS crappy Temu dresser appeared over the weekend, after 3 arguments with C about this shit, I finally got my organizer back. Solely because the POS dresser magically appeared from his parents house from her birthday.

So. I had another chat with C yesterday about how low it puts me on the totem pole and how, I *personally* think, if you strip away everything else, the bottom line of it is this:

I brought an item to the home.
B liked it and wanted it.
B asked C.
C said, and he has stuck to this exact story, "I isn't mine, it's H's, you'll have to ask her."
B didn't want to do that because she doesn't like me, but she doesn't like anyone (and she is truly mean and nasty to everyone...she barely has friends that even come around anymore because she's so snotty...).
B ignored C's response, did not ask me, and took it.

While I know exactly where the item is, I wanted that, it came here for a reason. Stripped all the way down, it's stealing.

And when I confronted C about it, he said, "She probably just got excited."

..........I'm struggling to accept that. It feels like the world's shittiest response and he just didn't want to deal with it. I have told him that by knowing all of this information and seeing it in her room and HIM not saying something as her father (because I would have done so, but it would have absolutely blown the lid off the house. I kept my mouth shut except to my boyfriend, to deal with his daughter)...by him not saying anything, he has, in her eyes, condoned her behavior and thus enforced yet again she can have whatever she wants, without asking. ((I also want to add, it is NOT like she had nowhere else for the TV she put on top to go. She actually, in fact, had a TV stand prior and forced her dad to take it out so she could evidently drag my piece in and use it instead. Beyond that, she has about 3 different pieces of furniture she could have put it on, plus a wall mount that could easily be installed and locale would never be an issue.))

So I come to you. Neurodivergent, neurotypical, everyone...please help. Am I just being an asshole because it was MY thing she took? Or is my boyfriend the asshole for not dealing with the fact that his daughter TOOK my property without asking, and even when I've argued with him about this at least 3-4x since then, told him I wanted it back, he did nothing. "We knew where it was and I don't think she did it purposely" is the feedback I got. And when I got super upset about it yesterday, he basically said he didn't see the problem because I have it back now.

...............2 months later. (??????)

If this situation were to happen to you, in my shoes, would you be upset?

If this happened to you and you were my boyfriend, being told that your child was directly informed they needed to ask permission of your significant other to take something and they didn't, and your significant other brought it up (the first time really, but 4 times minimum over the time span), would you fix it? Or is this really not at big deal?

TLDR; my boyfriend's daughter was told an item was mine and she needed to ask if she could have it. She never did that. I told my boyfriend she didn't ask 2 months ago, and the situation wasn't rectified until this weekend what a magic piece of furniture arrived for her 3rd "new room makeover" this year. It was not taken for a lack of space, it was taken per my boyfriend, "she got excited and forgot to ask", but in my eyes, she didn't want to ask and wanted to take my item. My boyfriend didn't do anything about it even after 4 arguments explaining, until Saturday, 2 months later. If the new furniture hadn't appeared, I guarantee my furniture would STILL be in her room. Please help! Am I wrong for feeling pissed off and small, and like I don't matter? Or is my ADHD brain being chaotic, and this is the normal for neurotypical type A people (he is that to a T, I swear).