Why do I feel like I'm cheating on him still, even though we broke up months ago?

I feel this way too. I guess we feel this way because in our heart the relationship is not over.. we still have hope that he will come back and we will be able to solve everything. Accepting a break up isn’t easy. Even if we are the one who decided to break, getting over someone it is hard. A friend recently told me there is even an hormonal explanations. After having been in an exclusive relationship for a while, your body gets used to certain smells, and approaching to someone new, with different hormones and smell, it is something we automatically reject

Healing takes time, which can be frustrating. While you may have broken up weeks, months or years ago they can still hold a place in your heart. An emotional connection with someone can be hard to get over and your heart may still be attached even though your brain is not. Allow yourself the time to heal and you may find the feeling of cheating goes away on its own as you reconnect with yourself. In the meantime remember that you are going through a hard time and to take care of yourself both physically and mentally. You can do this!

In times like these, it sounds like there is missing closure to be had. I remember how much I could breathe after having closure.

Maybe because the love you've had for him is still there and it may not have sunk in that you arnt together anymore eventually you will come to terms with it

Maybe because you think that you should still be with him even though sometimes that may not be the case

Maybe it's because you don't trust yourself because of the past or maybe because of guilt or abuse due to the cheating

You are still im love with the feeling of loving him. First you need to get rid of this feeling if you are sure about the breakup

Maybe you should think about if you have any feeling left for him, and if so what kind of feelings?

Many people feel this especially if it was a long relationship but you shouldn't feel this way you guys broke up for a reason

I think it is because you love him and are not over him yet. Try to get along and work things out with your new partner/interest.