I don’t think it’s about wanting to create drama, Juni, I don’t think that’s the point at all. But that doesn’t mean the OP would be acting with the best of intentions. Her mate is broken hearted and suicidal at the moment because of this man, so of course she’s angry. It’s about revenge on behalf of her friend, I think.
I’ve been in your place, OP. After my DSis’s marriage broke up, she confided in me that he had been violent to her. But she didn’t want us to say anything negative about him to anyone, as she was afraid that it would make things worse for her. Bad mouthing her ex might have made me felt good, and it might have shamed her ex, but it wouldn’t have helped my DSis at all.
And now it doesn’t matter; my DSis has moved on and is happily married to her second DH with her own family.
I can understand you wanting this man to pay for hurting your friend, but it won’t make your friend feel any better. It might make things worse for her, as the wife probably won’t believe that she didn’t know he was married.
Your job is to help your friend through her pain.