I dont know how to forgive

I have been in a relationship with a woman for over 9 years we have been married right at 4 and we have had a lot of problems in the last year especially. There has been so much that is going on that it would be a book I were to put it all down here. She was saying another man and even though she has claimed it wasn't a physical relationship I simply don't believe her and even if it wasn't. She went to him for emotional support and financial support. I haven't been an angel myself but I had never cheated on her. She simply wants to ignore the problems and thanks that theyll just go away. In the last month we have been trying to work things out but I cant get this out of my head and cant even be intimate with her.