There's a subtle -- but distinct -- difference between "ultimatums" and "boundaries."
"I forbid you to sleep with another man!" is an ultimatum. It's OTHER-focused, it's controlling, and will come across as such.
A BOUNDARY, on the other hand, goes like this: "Look, you're a grown woman, I'm not going to tell you what to do. What I DO think is only fair to let you know is that I will not remain in a marriage where my wife has unilaterally decided to invite a third person into it. I won't be my own wife's backup plan."
That is YOU-oriented.
There is an excellent example of this, by someone who stated it far better than I can. I'll try to find it and copy it here.
As for having unprotected sex with someone who is in an active affair, that's just foolish, dangerous and irresponsible. I don't think Chatterbug is saying anything that Won't Stop's own doctor wouldn't tell him.
