Hey Opti, should I say 'good to see you?' I hoped your non posting was a good sign. Anxiety attacks starting with H almost visible again?
This is coming from a non mother of her own birth children but I do have kid experience. Stepkids. Have you ever seen the show on ABC, Super Nanny? She prescribes a 'naughty corner' for behavior such as S4's. He needs boundaries and you are the one that has to set them and enforce them. Maybe you've already tried things but I suggest having him help you pick out his clothes the night before. If he throws a fit the next morning and gets uncontrollable he goes to the naughty corner for a designated time or until his fit is over - and he says he is sorry. The problem is this could take longer than you have to wait on a workday. You might have to take a day off of work but not let him know what you have planned. Or you could have him sleep in his clothes. Kidding! Maybe.
All of this is addressing the problem, but not what is causing the problem, which is your own anger. You've been patient for a long time, and you are close to reaping the rewards starting with weekend living with H and being a family. That itself is huge! You get a few days a week to figure out to get along and live together and then some time to let it settle while he goes back to base. (is that the right terminology?) The down side is the big swing every few days from mom/S to mom/S/dad, that can be tough for all of you. You are a smart woman, you will figure it out.
Live your life while you are still living. Riding the trail less traveled.