Pudmuddle, I wouldn't ask him to leave your home unless you are absolutely sure this is the right thing for you and your son. Once he's out of the house, he could very turn ugly and nasty and for now, even though you have to put up w/his behavior, at least he is under the same roof and sees his son.
The best thing I can advise you to do is live your life the best you can. Visualize him as a roommate and nothing more. If his behavior does get out of hand, you may end up having to sit him down and have a chat w/him about it and then advise him it might be best he leave. But for now, I'd sit tight, make sure you have some money squirreled away and watch your finances.
I know it's very difficult having them live at home, but there are others on this forum that have them at home and they may be able to give you some tips on how to deal w/him.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
