My mental illness is affecting my relationship. Advice?

Here's a little background: I was adopted at birth by distant and rich parents causing my abandonment issues and borderline personality disorder. Then my nannies husband sexually molested me for 8 years causing the PTSD. I understand life and especially relationships will never be normal or easy for me. I've tried talking to my boyfriend and explaining this but our relationship is falling apart because of my neediness, fears, and self esteem problems. I don't know if he can handle it, I know he loves me and I love him very intensely but after only six months were fighting a lot and my insecurity is getting the better of me. Even our sex life which has always been great is dwindling. I know this is the man I want to marry someday and spend the rest of my life with but I don't know how to get through ALL of this. Any one of my mental illnesses would make a relationship hard but I feel like all these together just makes it impossible. Any advice? What should I do?