Thank you for the good advice.
Unless he changes his mind, we will be getting what is called a 'voluntary' divorce here. As we have no children together, it should take -- from what I was told by a lawyer and what I read -- approximately 5 weeks.
If he decides to get nasty, I will opt for the 'necessary' divorce, in which I will have to produce evidence of his infidelities. That's not difficult (see my tagline below about the OC+); however, I know he does not want me dragging his escapades into the light, since some of them should have landed him in jail. (Allow me to add that at no time while they were happening was I aware of it, nor would I willingly withhold information from the local authorities; however, the statute of limitations had passed on these by the time I found out that it was all true. Also the current soon-to-be-born OC is by a legal adult, albeit barely legal)
So I'm fairly sure that we will be going the quick, less expensive route -- even if it's only to save his own goose from being cooked. Public humiliation is not exactly something he would want, and if he wanted to get nasty I could not only make it very ugly for him here but also tell his entire family about the girls, their ages, and another really horrifying fact of which they know nothing. Knowledge is power, after all.
As for those who said not to put anything in writing until it's finalized and that by then I won't care, I'm sure that's very good advice especially since he's running around now with a fleabag crooked lawyer for a friend.
My one trump card (other than my intimate knowledge of potentially damaging escapades) is that he never has any money. He couldn't afford to pay the fleabag lawyer, who doesn't work for free.
Also, he has been expelled from our church. So he knows that once divorced, he is not supposed to talk to me. But since I've been his codependent all these years, I know it will be hard for him to just quit cold turkey. And I want nothing more to do with him once it's all final!