Thanks to all for your advice and thoughts. I still feel eaten up by this but I can also see the futility of the situation. It was her decision to let him in, and even if she agreed that a boundary was crossed there's no way of undoing it thus far. So I'll let sleeping dogs lay and simply ask not to be informed of anything else about him. It's not an ideal solution but it will allow her to have her fun, and I won't have to feel tormented.

Thanks again.

~Tim