Bad news mate, sorry to here it, but as said, keep your cool, you want to be walking away with house, belongings and savings if you can, plenty time for arse kicking revenges later on, for now, play the wounded puppy and let her look the bitch.

Look on it another way, the fella may not be to keen on a family situation and when you've booted her out, he may turn his back and run, leaving her up shit creek with out a paddle. It's one thing to be seeing a bird on the side, it's another when they want to move in.

Also, is he seeing anyone, he may be married himself, might be worth finding out his address and having a look to see if he has a wifey, then let her know the crack, that is once you have your game plan in place.

Hope you get it sorted and come out on top, may not seem it now but things happen for a reason and a new door opens when you least expect it, misses perfect may be just around the corner