Such a dilemma

My ex wife’s uncle has been in my DM’s for a while now. I like messaging with him because he’s funny and nice. It’s gotten a little sexual at times and I like that too. He’s probably in his late 60s and a good looking manly man. He’s been divorced at least twice. Anyway, I know what he wants and I do too but I don’t know how my ex would react if we did something and she found out. We have a very good relationship and I don’t want to mess that up. I thought about letting her know I’ve been talking with him to see how she’d react. But I don’t want to out the guy either. Sigh