Putting down "my" dog tomorrow and I don't know how to feel

My sister's about 14 years older than me. She brought a puppy when she was in college and I was 9. She asked my mom beforehand if she could get a dog, mom said no, and then she up and brought a dog into the house anyways lol.

She took care of it for all of 2 years before she graduated college, moved out of the city, found a boyfriend, and kind of just outright forgot about the dog. We - meaning myself and my parents - had to care for it in our family home. This dog became my "impromptu" childhood dog.

I never was much of a dog person. I'm not one of those dogfree/hardcore anti-dog people at all, but I am just neutral. I simply wouldn't have gotten a dog/other pet by myself if it wasn't for her.

Make no mistake, I did like Peanut in the "oh hey there buddy" kind of way, but I was never all-in on the affection because I simply didn't have it, and despite my attempts to, I couldn't truly "love" this dog. My parents were the primary caretakers of him, I was just mostly refilling his bowls now and again and sometimes walking him/scratching his head. But I didn't cuddle him, I didn't go out of my way to spoil him, didn't "babytalk" at him or anything, etc.

To me, Peanut was just a presence in the house that's always been there, someone to be mindful of when you set the table for food because he might leap onto a chair and try to steal a bite. The attachment here just kind of formed from proximity + time. For what it's worth, Peanut never "like" liked me either. He preferred my sister/mom.

Now that Peanut's 17, blind, and almost incontinent, it's time. He's going to be put to sleep tomorrow - it's my responsibility to handle it because my parents are away and my sister is in a different city with 3 kids to take care of.

And right now I don't know how I'm supposed to feel about it, at all.

Sad that I'm going to lose him? Absolutely. But not in the "deep grief" way that you'd feel when you look up topics about euthanizing your dog online - I feel like I'm in this weird emotional liminal space where half of me thinks "well, you've never LIKE liked him, Peanut didn't even like you all that much either, it's going to suck for a few days but you'll get over it" ... and the other half suddenly realizes I've known this dog since I could retain memories and after tomorrow I'm never going to see him again. When he dies, I feel like so does the remnants of my childhood. My emotions feels like two puzzle pieces that SHOULD click in place but just don't.

And part of me, despite myself, is still bitter at my sister. It's not deep, but it's persistent, and it's there. I know she never intended for things to end up this way but at the same time. Dude. Mom told you explicitly not to do this. You did it anyways, and convinced mom to keep it because you genuinely wanted the dog. And then when you graduated you just ... left the dog with the family instead of taking it with you.

I might sound like a transactional asshole by saying this but I think the choice to get a dog comes with the implicit understanding that you accept the joy and love that the animal will bring you in exchange for 1) the labor that comes with caring for them, and more importantly, I think, 2) the genuine grief that you'd feel when you have to send them over the rainbow bridge. You know the saying: the worse you mourn, the more that means you genuinely loved them.

It just feels unnatural that I have to be there as this dog that I can't really even call "mine" (I didn't buy him, I didn't care for him the deepest, I just existed next to him for almost two decades) departs this world. I feel like I'm paying an emotional toll I didn't agree to, even if that sentence sounds HELLA entitled (I know, but it's genuinely how I feel).

I wish I could love him more. Or less. At least then I could feel fully emotionally committed one way or the other instead of this limbo. I REALLY WISH I could feel more strongly about this but I ... can't? The emotional connection just isn't there. It's weird and sad as hell. Idk what I'm going to do. If I should be in the room with him. I hate this.

Should I go through tonight sober or drink? I don't even know.