They may have been together for quite some time before marrying. Once the glow of the honeymoon stage dimmed, life began to take hold, i.e., bills to pay, jobs to work and...don't forget that during the pre-marriage some people are on their best behavior and once the ring is on the finger, then it's not long before the real self comes out to play. MLCers are very good at playing the victim and/or the good guy/gal, but all of that can change if they know that they have reeled in a partner who is willing to marrying them.
I would venture to say that he will hook up w/someone else. Some do this and others will travel the road of self by being by themselves. There are those who don't have affairs and/or marry affair partners and yet they seem to manage to work on their issues and some do come out the other side okay. It all depends upon the person, their personality and childhood issues. Your h could be one of those who will always play the victim and cry "poor me" to anyone that will listen. Time will tell now that the marriage is over.
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.