Origami, it's great to hear from you and hear what is going on. I'm sorry you are having to deal with this. Nineteen-year-old young men, especially DCs, are a challenge!
It sounds like from your post even from Saturday you are gaining clarity. It also sounds like his wife, who sounds fairly mature and sweet, is clouding the issue.
One of the key things I learned through all of this is to act with reasonableness. One of the challenges we face is we keep quiet and keep quiet and keep quiet, and the resentment builds, and the we blow our tops and say all kinds of things.
Instead, if you can wait until you are calm and keep it very simple, just a few boundaries with clear simple consequences, it might help.
1. Move out date. What is reasonable? 30 days? 60 days? Be reasonable, be clear and communicate to both the son and his wife at the same time so they have plenty of notice and are very clear about the timeline.
2. Chores. Have him and her both do a few every week. Keep it reasonable. If they don't, what? Just a simple consequences.
3. Money. If you are giving them any, stop. Give them notice that it's going to stop.
4. Looking back, one thing I think would have really helped me is to make sure he left the house when everybody else did, whether he had a job or not. I know others have done this, and their Difficult Child is out of the house from 8 until 5, or whatever the hours are. Most people are going to finally find something to do, and perhaps that's get a job.
We all know that if nothing changes, nothing changes. We have to be the change.
Remember he is very immature at age 19. Keep it clear and simple and try not to do it when you're mad.
It won't go smoothly, and be all pretty and perfect, but it's a start. We have to push them so they have a chance to grow up. if we just sit and hope and pray they will grow up, and keep things comfortable for them, it only delays the inevitable. We grow most when we are uncomfortable, and so do they.
Hang in there and keep us posted! This stuff is exhausting and very hard.