I was in a similar situation not too long ago.

When I started dating my boyfriend (with whom I have been for 8 months now), he was still talking to his ex. I told him it made me uncomfortable. He then saw her at a party twice and we had a huge fight. This led him to stop talking to her. He said he loved me and didn’t want to do something that would bother me or make me uncomfortable. We have also been talking about getting married very early in our relationship, so I knew I could trust him when he said he would stop. But the thing is, I just can’t let go. Just like you, I have cheated and been cheated on in the past. We still fight over petty things regarding his past, but only because I am the one bringing this up.

I guess my advice to you would be to have a deep conversation with him. Don’t be too accusing, but rather focus on the reasons why it makes you uncomfortable. I have seen how my boyfriend seemed offended whenever I said “I can’t trust you if you keep talking to her”, but when I told him how it made me feel and why it bothered me so much, we were able to have a constructive conversation.

Some people might say that as long as they are friends, you have nothing to worried about -but I disagree, because of my personal experience. Like you, I wanted to and still am working on myself. Learning how to not be afraid of happiness, to trust someone I want to spend the rest of my life with, and to not let the past take over my emotions.

I hope this helps!