Dawn, I am so sorry you had to witness the exchange, but at least you now know that the man you married is still somewhere within the shell of the man sitting in your home. You now know where his head is at and it's not at home w/you.
Take some time to figure out what you want to do. Don't do anything until you've calmed down and had a good "think tank" time.
Please take care of yourself.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.