What’s considered cheating ..

So recently I found out my spouse “supposedly” only considered cheating with his friend of 14 years sister back while I was pregnant.. supposedly ( long story short ) she made some comments one evening when he was waiting for his friend , it was supposedly just conversation .. he messaged her later that evening and then she said oh I was just kidding and whatever and went and told her mom who then told his friend and what not .. I just found this out this was back in September I’m now 3 months pp and I’m already struggling with PPD .. I’m managing but this hurts me a lot because my relationship before this was very abusive and manipulative .. I didn’t start dating right away my wall was up and I focused on my son and myself .. I’m hurt because I feel like the only reason supposedly nothing physical happen was because she supposedly rejected him ... I feel like there’s more to it but at the same I think I’m just assuming more happen because of the situation...

I just want some opinions please don’t be rude that’s the last thing I need is to feel attacked when I just need someone to talk to me ..