You precious thing. Even after all these years of pain and regret and holding everything in, you are able to spill it out because you need help. Sexual abuse through family members is too common and happens so easily because we trust these family members and feel like we betray them if we confront them or "tattle." What happened to you was so very, very wrong. You were a victim. There is not guilt for you to own. No shame. YOU are amazing. Please keep trying! I hope it's ok that I'm praying for you and praying hard!
I suppose your therapist has pointed out to you that none of this is your fault, and the victim should not take on the blame that belongs to the abuser. I would try to get away from the family, if you can. Did you ever tell your husband how horrible these cousins were to you? You don't have to tell him about your wild sex life between age 16 and 20, but he could help shield you from your cousin who is still so cruel to you and would certainly understand why you don't want to be around your family. They set you up. It's not your fault.
We live in a sick world and I am so sorry for your pain. You are not responsible for anything that happened and you need to remind yourself of this every time it pops in your head! You are the victim. Do not beat yourself up! Bad crap happens all the time and I am very sorry that this happened to you. God loves you and you are not to blame. Press on and focus on your husband and kids and refuse any feelings of guilt from sneaking in. Maybe your abusers do have regrets, but I personally would stay away from them. I would inform my family of what happened in the past and refuse to be in the same room with them, dredges up too much pain that you don't deserve. Good luck and God bless!