I agree with Stuck. You are literally letting her eat her cake and icing. She needs to see your boundaries set. She needs to respect you again. It was great you were nice to her just like I'm sure you were nice to all the other moms. But, she just like the other moms are currently screwing other guys. Is she sorry. I sure haven't seen that. I haven't read about any remorse or accountability. And until she see's you TOTALLY DETACHED and RESPECTS you again you never will.
I know this sucks, but you are just seeing the REAL her. Better now then in 20 years. Not everyone is this screwed up. Not everyone is unwilling to look at themselves in the mirror and admit they have problems to WORK on.
I really hope for her sake she still has the strength to do that. She will soon realize that she has made the biggest mistake of her life and have to live with that guilt. She is already seeing the type of guys that are out there and willing to screw around with someone who is "seperated".
Just keep on detaching and sticking to your boundaries. If she's worth it she will be willing to FIGHT for it.