Yes

Are we friends? Why is he trying to reach out?

Umm no

I have before, but Ill NEVER do it again

no

No

Yes, but how much of the conversation I entertain would be limited

yes

Not while he's in that relationship. If he'd do that to them, he'd do it to you someday

It would depend on the way he was reaching out to me/what he would say. If the ex was flirting with me while he was in an exclusive relationship I'd tell him that I'm not okay with that. If that wasn't respected I'd stop responding