Here's the bottom line:
You don't have to provide room and board for him, but you did . . . . as a gift. I have paid rent for someone else when they fell on hard times and needed it as a gift, so I completely understand that. If you love someone, that's what you do. But, as you have realized, it shouldn't & cannot be the plan for the indefinite future.
He now has income and needs to decide:
1) does he want to continue living in your house if it will now cost him $X (which I think should be half, and he's still getting a great deal, YMMV)
or
2) does he want to live somewhere else that will cost him $Y.
The "here are the TOTAL bills including full mortgage payment, utilities, etc. What do you think is a fair amount to contribute going forward?" conversation will be enlightening. Maybe what he will say is half or perhaps even more because he wants to pay you back in some way? That would be a good sign. If it's a lot less than what you were thinking would be fair, then you need to simply ask him what his reasoning is regarding why that is a fair amount (no need to argue, just see what his thought process is), and then you need to think very long and hard about this relationship if his thought processes are radically different from yours or if the angles he uses to justify the amount are advantaging him too much to your disadvantage.
Part of me strongly agrees with viper. I've learned from experience that if you give someone something out of the goodness of your heart, then some folks will be grateful but on the other hand some folks will immediately take what you gave already for granted and immediately expect that and then some more going forward. There are also even folks who figure out they can float around not paying their share, and that becomes the way they operate in life. The not wanting you to buy mouthwash and the contribution to the landscaping initially were good signs, but complaining about the yard work and then giving the cold shoulder when your broached finances are bad signs.
Good luck!