Quitting Job

My youngest son says he cannot do his new job.  It is too hard and too demanding and too stressful.   I talked him into not just walking out, so he went today, but he is going to tell them he can't handle it and give notice today.
There are no words.  This was my ticket to a new life where I wouldn't have to put up with him.  He would have enough money to just barely squeak by on his own and was supposed to move out in June when his girlfriend graduates.  Now we go back to fighting about appliciations and him being financially dependent on us.
Huge tension headache, no sleep and so upset.