mother :/

So to start this off my mother and I have never had a great mother daughter relationship, far from it actually. We have been trying to work on our relationship lately by going to therapy and everything because I want my mom back. So during our therapy session I ask her questions that I truly wanted answers too. All regarding my pos brother. Why didn't she report him? Why did she cover for him? That type of stuff. And I get it I do but her son took away my innocence! He raped me several times as a kid and she did nothing. Our agreement was we would be honest and open with one another about everything. Well I found out last night that she has been keeping something from me and I had to find out through my mils Facebook page. I don't know why it bothers me this mich because I never said "don't have a relationship with him" but I don't think she should reward him either. She is taking him on vacation with her my step dad and my niece and nephews. Like wtf? He isn't there for his kids hence her raising them but hey let's go ahead and take you on vacation with us! Wtf 🙄😒😡😤😶😑😮🤢I am at a complete loss and don't want to approach her at the moment so I don't say something out of anger. Just needed to vent. Sorry