Being calm is good. I agree don't guilt her or try to convince her of anything.
It's up to you to set your boundaries though. Explain what you will or will not accept in your marriage and what the consequences are for non compliance. Have you asked her to drop him?
M: A really long time. Crisis: 5 years. She's still worth it.
Life is never made unbearable by circumstances, but only by lack of meaning and purpose. -Viktor Frankl
