Mrs D, we warned you he would get all pathetic and tug at your heart-strings, and sure enough. This is the response of an emotional child. A normal 'sick' person would be grateful and do what they could to contribute and help.
Now he is deliberately challenging your boundary. Can I suggest you seek legal advice?
Don't liaise with his parents because you're buying into his drama then. It's up to him to work out where he'll go. He's only a child in his maturity; he can work things out himself. And you cannot 'send' him to his parents, as he's not a parcel.
Make your plans, and make them stick. The longer he's around, leaching off your energy and good-will, the harder it will be to make him leave. You need to be very, very, strong because he'll do the pathetic helpless child over and over. Why shouldn't he? It's always worked in the past.