Very helpful advice, thanks. We don't have children and there isn't any evidence of a physical affair, so not sure how things would go. I'll think of my questions, do some reading, and reach out to a lawyer.
One of the things that I recommend, if you are able to do this, is to go into a "business mode" and try to keep personal feelings out of it. Because, really, that's what it's about to become. Prepare for the worst and tell your lawyer everything...anything that your H may be able to use against you, because believe me, he will.
There are moments in this life when you are so confident in the rightness of your actions, that not even for a second do you consider the option that you might be wrong.