M, I am so very sorry that you found out the information as I know how hurtful it is. But, if it provided clarity for you, then it is helpful.
Snodderly, as usual, gave you all the right advice. If you plan on telling him what you know, he will try to turn it around on you. He will get angry and accuse you of snooping. Dont let it throw you.
Calm, resolute, and strong is key here. My quess is he wont leave right away although there is the possibility of him storming out.
No matter, you will be ok. If there is the possibility of him going on a gambling binge, it might be necessary for you to take steps to protect your money.
When you are ready in the next week, try to see a lawyer. Most allow for a free consultation. Have questions written down.
But for now, take good care. As Snodderly said, initially you will feel all sorts of things - anger, sadness, fear. But then you will feel a certain calm.
