Thinking About my ex while in a new relationship

Hi everyone,

I am in a relationship. Yet I keep thinking about my ex. It’s been almost 3 years since we broke up from our 2 year relationship highschool love. And I’ve been in other relationships after him, and to add to that I did cheat on him (which plagues me to this day) and we ended Badly. We communicate from Time to time to say happy birthday. And I know i do not deserve him. When i asked him he said there’s no hope to rekindle what we had but I️t would be a miracle if I️t did. Which is why i tend to leave him alone. But i do still think about him even in my current relationship. And i do not want to. I do not know why i do either . Can anyone help me? When I’m with my current boyfriend i do not think about him but there are times when we are apart when i think of my ex.

I don’t know what to say to my current bf. Because there are times that i suddenly burst out crying remembering the horrible things i did. And he thinks I’m not over my ex. But i want to be with my current bf. I want to start new.