I think you should spend the most time with your girlfriend and so maybe this can help you forget! And when you're alone or free or anything then whenever this thing comes in your mind then just tell your mind to shut up and that to forget the past and that your girlfriend loves you and all that and so just forget the past! Because the bright future is ahead!
My Girlfriend had physical relation ship with her ex -boy firend. Although I forgive her but still every day I feel bad for the last six months - continuously thinking about this. Kindly give me advice about how to forget it?
I think that you need to spend as much time with her as possible. And if you are still feeling the way you are feeling, talk to her about it. It might help. :)