Are they married? Yes about two years

Did you know the cheater or the cheated first? I dated the non cheater several years ago. We have remained friends (attended their wedding etc).

Does the cheater know you know? Yes he knows. He asked me to cover for him so he could meet is new 'love interest'....yes i declined to participate in the ruse

Do you all hang out regularly? the cheater is a guy who i go mountain biking with sometimes

How long have they been in the relationship (if they aren't married)? Married about two years. Dated about 2 years before that...

Do they live together? yes

Are you close friends with both...one more than the other...and for how long? I am not close but know them well.

thanks all for the advice