Dear Keke and Kat: Ex Dating Married Woman

Ahh.. the classic "friends with my ex" story.. where you end up finding out more than you probably should or want to.

She's concerned that there's about to be some drama popping off due to her ex seeing a married woman.. who claims she's separated but not planning on getting an actual divorce due to time constraints. Hmm. Sounds fishy- but does she let her ex's girlfriend's husband know what's going on? Or stay out of it?