My ex-husband is refusing to leave the house. The deed is in my name as part of property settlement. How do I get him out?

Yes, he's now a squatter, and more particularly he's a trespasser.  I'd suggest a trip to your local police station, with your "official" divorce decree and a photocopy to leave behind, and see, first, if you can get him removed that way;  if it's necessary to first file a complaint against him for the trespassing, I'm sure that won't slow you down and it shouldn't.

There's another way, assuming that he doesn't physically stay on the property 24/7:  as the owner of the house, you have every right to have all the locks changed, and refuse to give him a key.  And if he then breaks in, he's guilty of burglary.  If the police don't deal with that, then you need to hire a lawyer to provide them with some "education."

If he makes any threat of violence at all, please go immediately to file a complaint for domestic violence, and get a "PFA" (protection from abuse) order, to remove him from the house and make him stay away from you.