Having fun with my x-husbands cousin.

I have been divorced for about 15 years. Last year I was introduced to my x-husbands cousin. Within the last month I have seen him 3 times and we have had sex every time. We haven’t told anyone that we are taking. I guess we both know we will get drama but we are having fun and not serious so it wasn’t an issue. I talked to my x-husband a few days ago, yes we are actually good friends, he was drunk and said that if his current relationship didn’t work out that he would like to try with me again. I don’t love him and we have no future, that is very clear to me. Since he was drunk I know he won’t remember telling me, he forgets stuff even when he is not drunk. I feel bad and know I can’t tell them about each other. Should I end it with his cousin? Should I stop talking to my x?

Update: I’m done with the cousin but I’m still friends with my x. I don’t have kids with either, fyi.