Sunshine, it is normal to feel rage. Just don't act on it because it gives them a lot of satisfaction to see you in such pain. WAS's and their slimes just l-o-o-o-o-ve to rub your face in it.
And think about this:
If they were soooo happy, why would they feel the need to rub your face in it? Because their new relationship is just not enough for them. They need to add as much drama to it as possible.
So, be mad all you want, just don't act on it or say anything to your son or your friends. Just don't.
WAS's and their slimes remind me of Cuckoos:
The cuckoo migrates northwards in spring to breed. During May the female begins searching for suitable nests in which to lay her eggs. The cuckoo always chooses nests belonging to one species to lay in, probably the same species that reared her. Before laying an egg, she removes one of the host's own eggs from the nest. She may lay up to 12 eggs in this way, each in a separate nest.
Cuckoos can't even build their own nests. They steal them and kick out the eggs. Pretty icky.