While I don't necessarily disagree with the "better safe than sorry" theory, there's a key element to this that is being over looked.
She cast a spell to prevent him from being with anyone else. Yet the man in question is not only with the poster, but has a child with her. Sounds like the "spell" if cast, didn't work.
Personally, I wouldn't want a man who was incapable of remaining faithful, child involved or not.
Cleanse your house and family if you so choose and look up any uncrossing you wish, but keep in mind, at the end of the day, blaming a spell for relationship issues only masks what's really going on.