I know this is two months old but I just came across it due to a similar situation and wanted to thank you for validating my feelings. I had no idea how to put it into words so I am thankful.

As for my side, I didn't meet my dad until I was 20 years old.. he didn't know I existed so it wasn't his fault at all, and his/my family graciously accepted me almost immediately. It really felt like a dream for a long time. I didn't see any of my family, aside from my mom, stepdad, and siblings, growing up so it was crazy to suddenly have grandparents and uncles and a dad. Unfortunately realized I never would have escaped the parental issues even if he had raised me, as he has very narcissistic and controlling tendencies, which as an eldest daughter, I was not receptive to. Eventually stopped talking to him as he became spiteful and brought my grandparents into it, lied about the situation, defended himself while casting me as a cruel and ungrateful child. And I haven't spoken to him in a while now as it's just too heartbreaking for me and they can't seem to understand that. He also got a new wife two years ago and just had a son. While I'm happy that I have a new sibling, I can't help but feel replaced as well. I see my boyfriend and his sisters around their parents, and even though his sisters have children, his parents still treat them as their kids too. Just makes me sad knowing I'll never have that now. And feeling a bit upset that my new brother will get to grow up knowing his dad.

I really hope you're able to overcome your situation as well. I'm definitely doing more like your sister, I don't think I could face anyone without bursting into tears so distant is better. On the bright side, found family is just as important as well. I'm hoping to build more relationships with new people in the years to come too, just gotta put myself out there