May be your husband has a point?
your son is 22 and old enough to know that he needs to seek professional help for his past.
Is your son willing to seek that help? If so, would your husband be willing to come home?
Until your son does his part, im afraid I'm partially in agreement with your husband, i'd find living like that intolerable too, there's only so much sympathy you can give someone and his has obviously reached his limit.
I appreciate my point of view will more than likely differ from everyone elses who'll see that your loyalties lie with your son, and they do, but they also lie with your husband, daughter and your marriage, and ultimately your ownhappiness as well.
Good luck- whatever the outcome.