I have learned on here that you have to feel it to heal it. I don't think suppressing the feelings or thoughts is healthy.
I do think that sometimes it is self harming to allow yourself to go to that dark place on a regular basis, to 'go there' every time. (Not sure if I'm expressing myself clearly. I don't want to convey that the feelings are voluntary and/or controllable, it's the response to the feelings that you can work on).
Maybe the thing to work on is allowing yourself to feel the feelings, and then gently let them go. Give yourself permission to feel that pain, but don't wallow in it. I guess the goal is to get to the point of acceptance. That you were cheated on, the pain is brutal, that you can't change it but you can move forward. I think in time this will get easier.
I hope any part of this post helps, Yakamishi. I'm sorry for your pain.