I need advice

I need advice. Does anyone have any? I feel pathetic for asking, but I'm at a loss. my sister moved back home, and she has done a lot of things in the past that have it sounds stupid, but traumatized me. I'm on medication and getting into therapy to trying to move on from everything that happened and accept it. I was doing really good, you know, getting better until she came back, and now I'm worse way worse like I've never been this bad, and I'm taking it a lot harder than I thought. I'm keeping myself locked in my room and isolating myself from everyone else. my parents dont deserve this and I know but I can't be near her. I just need some help on how I can get through this. I don't want this to be my life. I don't want to cry all the time. I was happier and I wanted to be happier again. can anyone give me some advice?