Hi wounded, sorry you are here, but you are in the right place. I would read as much as you can as fast as you can so you understand the dynamics of an affair and know what you are dealing with. Get your hands on Surviving an Affair by Willard Harley. [a bookstore or on this website] You should be in Plan A and that can start today, though.
The single most potent weapon you have in your hand is exposure. Affairs thrive on secrecy and exposure is ruinous to them. Affairs are fantasies and when they are exposed, it forces the affairees to see how sleazy they look through the eyes of others.
Good exposure targets are spouses, bosses, parents, pastors, siblings. In your case, I would contact the OW's boyfriend TODAY. Another good target would be your husbands parents. You simply give them the facts, tell them you are trying to save your marriage and ask for their help. Do NOT tell your H beforehand.
If this is a workplace affair, I would notify the head of Human Resources, your H's boss and the OW's boss.
You were absolutely correct in not leaving your home when your H asked you to leave. He should be the one to leave if he wants to leave.
In the meantime, do not lambast him, do not fight with him. He will try to bait you into fights and you can expect him to attempt to rewrite the history of your marriage ["I was unhappy for years," blah, blah, blah] This is all typical behavior of a fogged out wayward spouse. Don't listen to what he says, pay attention to what he DOES. Just don't make it worse by pushing him away with angry outbursts, etc.
I will post an outline of Plan A below, but in the meantime, read these links:
http://www.marriagebuilders.com/graphic/mbi8113_ab.htmlHow to Survive Infidelity:
http://www.marriagebuilders.com/graphic/mbi5525_qa.htmlDr. Harley's radio show is on every day from 10-1 cst and you call into his show and ask questions.
http://www.marriagebuilders.com/graphic/mbi5525_qa.html