I just need to vent/share.

I feel like compared to where I was 3 years ago with my mental health and accepting the abuse I had experienced throughout my childhood I am in a much better place. It no longer affects my relationship with my boyfriend (in the beginning of our relationship I had a hard time letting him touch me/be intimate) but I still have my moments where I completely breakdown and get so angry with the people who hurt me. So this is where I vent. My grandma's husband (not biologically related) abused not only me when I was 8 but abused my mother and 3 very close cousins of mine. Thankfully a few years later he was tried and sentenced then later deported. The issue that I have is that my grandma who basically raised me, had forgiven him and moved to Mexico to be with him once he was deported. I never shared with my mom that I had been abused (not just by him) mainly because I don't even know how to begin that conversation and I'm terrified that it'll open old wounds. I have somewhat accepted that he got his punishment but the fact that my grandma is able to live with him after knowing what he did to her daughter and grandchildren makes me incredibly hurt. I just don't know how to go about this.