AITAH for calling my girlfriend insecure about my relationship with my sister

I am genuinely confused because this issue has seemingly come out of nowhere and my girlfriend has stormed off to her best friend's apartment to spend the night there.

I (21m) have been dating Olivia (22f) for about two years, and we haven't really had major fights until tonight. I have a younger sister Anne (15f) and we're as close siblings can be with an age gap like ours.

I thought Olivia liked Annie because she showed zero animosity towards her or our relationship since I introduced them two years ago.

I was talking to Annie on the phone, or well honestly just letting her complain to me about something our stepdad did while I sat in the living room. Our parents tend to be too sensitive to talk about things like this so she usually rants to me about it.

Mid-conversation, Olivia came out of our bedroom, snatching the phone out of my hands, and abruptly ended the call with a " He's busy." before hanging up. I was stunned and asked why the hell would she do that.

Olivia went into a tangent about how I put Annie above her, and how it felt like I wanted to be with Annie instead of her, which deeply grossed me out. I argued back that I never put Annie above her in anything and it was super fucking weird of her to imply that I wanted that kind of relationship with my own sister.

Olivia tried to bring up examples of what she accused me of but I shot every one of them down:

• I spent a day on a trip with my sister. That trip was to my hometown, and it was Annie's birthday so of course I spent time with her and it's not like we were completely alone either, my family was obviously celebrating too. Olivia very much could've come along with us but chose not to.
• I send my sister money sometimes and I don't expect her to pay me like I do my girlfriend. Whenever I send Annie money, it's either near the holidays, her birthday, or so she can buy something like a winter coat or a book she wants. Besides, Annie doesn't have a job and we now live in different states. Also, I've never demanded that Olivia pay me back, she does it of her own free will and she doesn't even do it that often.
• Our " late night conversations." Whenever we aren't talking in person, it's usually just Annie talking about stuff she can't talk about to our parents, and whenever she talks to me " late at night" it's either that or she's asking me when I'm coming before a visit.

These are just the ones that threw me for a loop, there's more but I don't feel like typing it all out in this post. At the end of it, I flat out called her insecure over Annie and I's relationship and told her that she was freaking out over nothing.

Olivia was even more pissed at that and told me I was acting like a dick. She packed a night bag and went to her best friend Chloe's apartment who doesn't live too far from us.

Olivia has been ignoring my texts and calls, but Chloe and two of her other friends have been chewing me out over texts for what I said. They told me I was being an dismissive asshole and really hurt her feelings.

​