Struggling with Past Trauma and Guilt

I feel like I'm selfish and a liar. my childhood wasn't the best, but it wasn't the worst, so everytime I'm stuck in the past I feel so horrible because others have it worse than I do. I still live with my parents (separately, they're divorced) and whenever they get too close, talk to me, or get mad at me, I freak out because of past events and that I'm scared of them (especially my mom, who was my primary caregiver). I'm so scared all the time from loud noises and anger and people walking towards me or touching me, but I feel disingenuous because my parents are really nice sometimes and haven't done anything physical in years. and when they have it was deserved and a punishment. I just feel so horrible and selfish and I don't know what to do.