I get it. Not everything could be just logical. Of course it’s upsetting.

But you are asking what to do. There’s absolutely nothing you can do. Yes injustice is unfair but there’s nothing one can do in regards to what other people are saying or doing. Unless it’s becoming a legal issue. You have no control

There’s nothing you can do about him talking to mutual friends. It’s out of your control. If they want to be busy bodies and meddle in other peoples marriages, you don’t need them as friends anyways. And they know you two had marital problems and separated before so I doubt they’d want to listen on who did what. Let them talk.

There’s only one thing you can do. Not marry or get into relationships with types of people who do smear campaigns. But that ship sailed. Focus on what you can do, not on what you cannot. If you had a good therapist (not the one you have) it would be a great topic to discuss.

I get it you are upset but try to stay reasonable. It’s out of your control what’s he saying and to whom