Yay!
Another chance to say what I wish the entire world could here - swinging is not cheating and cheating is not swinging. I realize that cheaters are a part of the lifestyle, as is VD. Both are equally desirable...
You can't dictate who can show up at a swing club and of what moral timber they should be made of. Alternate lifestyles are crawling with vermin - and your boyfriend is part of that scum that gives us all a bad name.
Just get away from him. He is in the process of destroying his life and you've helped him along the way enough.
If I had one wish about the lifestyle, it would be that it was made exclusively of couples who have a strong, honest, communicative, adventuresome marriage.
Spoomonkey