In the Book "Loving God With All Your Mind" the author says that forgetting the past is essential in having peace of mind.
The past will stagnate our growth. It keeps us focused on pain and unhappiness. The past is not what is happening today. It has already gone. It is like when a child gets a balloon and the wind snatches it away. It is gone. The child will cry because it is gone but only for a short time.
We are allowed to grieve over the past for a short time. Then we need to say, "O.k., it is done. I am not going to think on it anymore."
When something painful comes to mind, think about something opposite to that. If you keep thinking about something your husband has done to hurt you, make yourself think about something good he did. Thank the Lord for the good thing that your husband did.