please help can't forgive bf

My bf hid still being in love with his ex and calling and messaging her for the first couple of months we dated. he lied about so many things including saying they didn't speak since . we dated as well as the fact they were cheating behind her bf back til they day we started seeing each other. He's lied about so much and fought with me about deleting her sexy photos, etc. I love him and it's in the past but I'm still so hurt and mad idk what to do, it also hurts that she talked bad about me to him and he never took up for me. he feels terrible but I don't trust him. he doesn't know what to do to fix it. Any advice on how I can feel better.