Just looking for advice. Any advice, really

Ive never written on one of these websites before, so i don't really know where to begin or what to expect. But here goes nothing... Im 18, engaged, and dealing with anxiety, depression, and PTSD. My life has been far from a fairy tale, between being raped and tormented as a child, to being molested by my step father for years. To be honest, I'm not quite sure i know the true meaning of love. As for my fiancé, we've been together for 2&1/2 years, and I've known him all my life. He truly has saved me from hell, and I'm currently living with him and his mother. We both work retail jobs, and his mom makes us pay rent every month. I see my mother every sunday at her house for dinner, along with my little brother who lives between my mother and my step father, (his bio father). My brother is 13, and he still has no idea the trauma his father put me through. I want to tell him, but i fear his reaction, and i don't want him to have hate towards me, or his father for that matter. I know what its like not to have a dad, and i don't want him to feel that way. To this day i still don't think my mom believes what happened to me. I think she was too caught up in love to realize what went on when she wasn't there. She says she believes me and that she puts me above her ex, but i don't see it. She stayed with him for years, even after i had told her what he was doing. But the second she found out he had cheated, is when she finally went through with a divorce. My fiancés mother is controlling and manipulative, and i honestly cant stand living here. But i feel like I'm stuck and this is the only choice i have right now. I refuse to stay with my mother because she moved back to the house that he molested me in after the divorce. I cant even walk in that house without getting flash backs and getting sick to my stomach. So i live with my fiancé, so at least i know my step father cant hurt me again. My fiancé protects me, he's my hero. But he's not perfect either. The beginning of our relationship he cheated, and ever since i haven't been able to trust him. I love him and i know he's not being unfaithful now, its been 2 years since this happened. But i just cant get over it. I feel like i need to know his every move and know everyone he's talking too. I guess the main reason that I'm writing this is to just get someone else's point of view. Am i wrong for feeling the way i do? Theres much more to my story, but i guess ill post more once i notice that someone will actually take the time to read it and help me out. Well, thanks for your time.

I definately don't think it's wrong to be feeling the way that you do. If i had gone through all of that i would probably feel the same way.