He Bought Wife

My wife worked in client relations for a big firm and a really wealthy client offered her a large amount of money if she conceived and carry his child. I am sterile and therefore not able to give her children. We agreed long ago that we didn't want children anyway.
She was let go for budget reasons and my company went under. We had fallen on hard times and eventually accepted the offer. My wife met with him a few times until she got a positive test result. It broke my heart to watch her bond with her unborn child and knowing it wasn't mine. The man was very accommodating. He took her to every appointment and would buy us loads of groceries, pay our bills, our mortgage payment. My wife slept with him a few times after she got pregnant. She thinks I don't know but I saw them do it a few times.
She has since given birth to the man's baby boy. Part of the agreement was that we don't have any contact with the baby or the man after birth and so far everyone has kept up with that part of the deal. My wife seems lost and depressed and even though we are financially stable now, this is the most unhappy I've ever seen her