It is time to sit down with yoour husband and decide on some ground rules. Also on consequences for not abiding iwth the rules. one rule is that until he is supporting himself, wife, children AND YOU & husband, he is not to EVER tell you how to spend your $$. Also that basic manner are to be observed or he can get out. I would not tolerate the rudeness & disrespect for another minute. Did you treat your parents that way? I would have been out quickly if my parents ever even thought they might have to call the cops on me.
If he isn't in school with a part time job then he needs to go out and figure out his own way in the world. It just is hwat adults do. If he is too good for a paying job, give him a list of chores, turn off the cable and internet (unplug the system during the day and take it with you if you need too) and tell him that he can have tv and internet if he has his chores done when you get home. those chores should include cleaning, dishes, laundry having a dinner ready and caring for any animals you have. Heck, get a cheap nanny cam and set it to record during the day to monitor him if need be. Can't cook? Get the boy a cookbook. All of these are life skills that he NEEDS and there is no time like the present for him to learn. If you are creative (turn off the air conditioning during the day too), you can make being at home FAR more work than any job and make him eager to get a job. I got one at 14 and still had a subtantial chore list, esp compared to my friends.
He may need a substantial kick in the pants to make him actually do the chores. Heck, he would not eat dinner in my home until he had it fixed for the rest of us, without trashing the kitchen. I am totally 100% serious about turning off at least the internet during the day for him. Computers are a huge time slurp and he likely has some degree of dependency on the computer. I think many teens do, esp those content to sit home all day. The first week of no internet will be awful but it should pick up if he can then earn computer use by getting his chore list done. You likely have to do some teaching for how to do chores, and some standard setting, but also give up some control. If he says product x works better, let him give it a try. My mom did all this and raised 2 kids who could run a house by age 16-17. Partly because she was totally unable to do basic chores due to her mom dying young and her dad hiring a housekeeper who didn't teach my mom anything about chores. We got them early and were capable. My friends with moms who didn't give them chores ended up with kids who didn't have the ability to run their own lives. My kids even difficult child had chores and got my creative consequences and all can do most household chores. My bro's ex refuses to make niece do any chores and niece is as useless as any child I have ever met. SHe isn't able to do chores and feels like she isn't able to do anything.
Another reason for chores is that the less you have to do, the less you get done. If you hve too much free time, you don't even get the minimum amt of stuff done. It is time for son to do things to support himself and to earn some confidence and self esteem. Keep him busy - loud cheerful music to wake him up, etc... I have a cousin who never did chores until he got a girlfriend. I adore this girl because she not only insisted that he help her father with things like yard projects, she also sat his idiot parents down and bawled them out for not making him do any chores at their home. She literally gave him chore lists and if he didn't do them to HER satisfaction (FAR higher than his parents), he could not spend time with her. She even gave his useless father some regular chores, lol! She was only 14 when hse started this, but she turned my cousin into a responsible young man and father. It was shocking and beautiful to watch the imposition of some structure and a few logical consequences change him into an enjoyable human being.
I don't think your son is capable of structuring his time right now. He suddenlly doesn't have anything to impose structure and likely doesn't know how to do it. It isn't fun, but imposing some chores and structure reallly can restore your relationship. My son hated me for several years, but now has openly thanked me for the chores and for fighting to make him learn how to do them and all the other things we insisted on. He could stop his medications if he wanted, but he has chosen to stay on them because he likes who he is when he is on them and able to use the tools we fought to teach him about life and working. We thought he would hate us forever, esp given all the fighting he did over even minor things like showering. But he didn't. Your son will fight, hence removing the internet, etc... and no dinner until he fixes it for all, etc.... But in a few years he will see the value of what you need to teach him.