I'm glad you stayed out of Mr F's relationship. Another factor that hasn't been mentioned is that he might be aware of the sleeping around. It seems important to him that he can do it, and he might have found someone who will accept it in return for the same (open relationship). Also, I don't think your evidence would be allowed in court. It's a strong hint, but it's hardly conclusive.
All very interesting stuff about New Guy.
M39 D6 D3 (at S) S 2014-09 D 2016-09
"You can't start a fire sitting around, crying over a broken heart" - Bruce Springsteen.