I went through this with my Ex who was not an A just psychotic. He ruled my thoughts for about 9 months until I was sick of it and I found a therapist to work through it. My therapist very quickly pointed out that most of the anger I had was at myself for letting someone treat me that way, and for becoming a door mat to someone who was treating me horribly.
I suggest therapy its very effective. Some things I did - At home alone was when the thoughts raged (they did at work too but I could distract there somewhat). So when I found myself replaying the whole thing for the millionth time I would leave my house, take a walk, exercise, find a project and work on it (I ended up renovating my house which also helped because it no longer contained memories of him). I got rid of everything that reminded me of him, pictures thrown a way, gifts were donated, clothes were donated - I got rid of all of that.
Someone mentioned music - I stopped listening to anything that would trigger sadness, or any thought of him. Getting rid of all physical memories really, really helped me as did the music part (it would trigger a cry/anger episode).
As for trusting people I use a little logic there. I don't know how old you are - I was 43 at that time. In review of people that mattered those that had been untrustworthy were few. Truly one bad apple doesn't spoil the whole bunch. Make a list of people who have been good to you and trustworthy it will be a longer one that she on the other side.
Finally, forgiving myself was how I moved on completely. It happened, I screwed up. no time machines and no opportunity to go back and handle things as they should have been handled. Gotta let go of the past and deal with the present. Along the way I found SR and Al Anon and dealt with my codependency and tendency to seek out troubled souls to fix them. Today if I met that same guy and replayed our romance it would have ended a month in the first time I caught him on a sex website. I never felt that i couldn't trust anyone, but I did feel I would never have another relationship given my history and some shady men - it was too painful. Who I couldn't trust was myself because it was ME who CHOSE those people. There were many men along the way that I hadn't given the time of day to that were great guys, but if they weren't royally screwed up they weren't for me.