Timeless, first I am so very sorry that your idiot WH is being such a jerk and has completely lost his fracken mind.
Second, I do not remember who said this but I think this is a line you need to give your WH. Tell him that he is free to go and screw anyone he wants, do what he wants and live where he wants...he just won't be doing it as YOUR HUSBAND!!
Third, do not let him know that you are aware of her name or her address.
Fourth, go see an attorney who will give you a free consult and see how much they charge to draw up divorce papers. If you can afford it have them drawn up and then have him served at HER address. Give him the fracken shock of is life. There are also places on line that will fill out the papers for a small fee and you can also get the forms from most courthouses and they have people who can help you fill them out. You do not have to file them with the court but you could have one of his friends serve him with the papers. Make sure it is a friend who would never condone what he is doing to you.
Just because you file for divorce or have the papers drawn up doesn't mean you have to divorce. You can withdraw it anytime before the final hearing. But you need to be very very clear with him that you will NOT tolerate his 6 month whore fest and you will divorce his sorry ass if he leaves.
If you do not have the money or want to file for divorce at this time then I would suggest you buy some large black trash bags and hand him the box. When he asks what they are for, smile and say "well I thought you would need them to put your crap in since you will no longer be coming back here to live."
If he asks what you will do during his 6 month sabbatical from the marriage, make up something. Tell him you will be changing the locks on the house, cleaning up the house so you can put it on the market, throwing away any of his left over crap, telling the kids what their father has done and why you are selling the home, then you will buy your own smaller home and fix it up. You will start dating again to find a man who will cherish you the way you deserve (don't actually do this one though) and one that is much better looking too. Tell him that you have always wanted to go on a cruise (or something fun) so that will be on your list as well. Make sure he realizes that while he is off doing his "thing" you will be moving on without him and having some fun of your own. You need to make sure he understands that you are NOT his back up plan in case "slutty mcslut face" isn't all that.
I have a feeling that he might change his mind about idea of taking a "break" from the marriage and if he doesn't then do you really want him back? He needs to see that there will be consequences for this sabbatical whore fest.