He says nothing happened but I don’t believe him.

My now ex says nothing happened and he was just being friendly but I don’t believe him and I wanna know if y’all would too or what y’all would do. I don’t believe him and I have always thought something was up, we talking about it and he said they just talked a little but that is still no excuse to me. The fact that you got on tinder and started talking to someone’s doesn’t label him as friendly to me it labels him as looking for trouble, so my question is would you end it? Because I did but second opinions are always needed to me. Thank you!