Long story short, I split from ex years ago due to him cheating plus other issues. 3 weeks ago we slept together and did so another 2 times. This is the first time we had sex for about 2 years. Last night he had sex with someone else and is saying that's ok as he is single. I'm very hurt and wondering how we can carry on the great co parenting relationship that we had. I don't know where to go from here??