I hate to say it, but I would deal with this woman over having your H interact with her. :/
I would try to find something about this woman that does NOT fit OW's description at all. Then whenever you see her and think of OW, immediately think of everything about this parent that is NOT like OW, and talk yourself out of those thoughts. With her daughter- same thing. Everytime you hear the name and trigger, look at the sweet little girl and remember that she is not a skanky whore- she is a sweet child in your daughter's class.
Hang in there!!
At least the current man "only" cyber-cheated.
"Love means never having to say you're sorry."
I try to go up to say hi to her regularly so that I can imprint the nice person she is on my brain instead of the OW. It is a trigger, however!