Dealing with childhood SA as an adult

Hello. I’ve posted on here about this before but long story short, my sister who is almost two years older than me assaulted me on multiple occasions when I was a child (I don’t fully remember my age but I couldn’t have been older than 11) it happened on multiple occasions and when I went to try and tell my mom about it she just stared at me and said “say no”. Which of course didn’t offer much help. It’s been most likely 10+ years since then and recently I haven’t been coping with it well. I have severe OCD and paranoia and I feel like I can’t trust my own thoughts and the people around me. Being introduced to that at a young age really messed me up for YEARS. Im upset that I never got help or therapy for it and I feel like it messed me up as a person while growing up. I’m mad at myself for trying to ignore it and being ignorant to its affect on me for so many years but I’m also mad that I didn’t get help when I needed it as a child. When I told my mom about it recently her first instinct was to worry about my sister instead and that really hurt me. I’m worried about her too but why does no one care what happened to me? Why did no one care what happened to me when I spoke up as a child? I feel sick and I can’t take living in this hole for much longer.