I`m sorry you are in such a difficult position. It sounds as though your son is taking advantage of you because as a mother you are used to the caring role.
Can you re-open a conversation with him about the extra demands on you from your husband`s PD and holding down your job and that you are becoming more and more worn down so you will no longer do his laundry, shopping, cooking, cleaning. He would have to do all this if he left home. If he doesn`t contribute financially to expenses I suggest you could think of those jobs he could do regularly in lieu of `rent` which he would also have to pay if he left home.
If this is not something that you feel you could tackle perhaps his grandparents could talk to him for you.
At 23 he is more than old enough to take responsibility for himself and to understand that unless he becomes a hermit he will have to learn to live supportively with other people.
If none of this works you may have to give a date by which he must leave and make him understand that renting a room in a shared house is the best he can expect and you won`t contribute. The alternative to this is to do all his own chores, contribute in some way to expenses and to stop making your house such a stressful place for you and your husband.
We are all wishing you well, knowing you will have to be both strong and determined to deal with this but at 23 he is unlikely to change unless brought up short.