Refusing treatment

My adult 23 year old son with Asd level-2, severe ocd, washing just hands for many many hours, refusing any sort of treatment at the moment. He has no job, not studying, does not shower, if we ask him to do anything gets agreesive

Not sure what to do, can we move him to a supported residential facility 

I have another younger child and life has just stopped, we can not go out leaving him alone as would not eat on his own for hours, needs constant prompting. 

Has not taken shower over 4 months, not gone out for last 5 months, just stays in his room

, eats barely one meal. 

  • Been in bathroom for more than 10 hrs today, it varies sometimes 2-3 hrs, sometimes for many hours. 

Just got a physchatric appointment for him but I worry he will not go and get very angry but will ask him anyway over the weekend 

We don't know what to do. 

I am myself feel very low most of the time as feel so stuck and not able to help him and get out of this situation.

Only if we can get some respite even for a few weeks and he can be at a safe place, looked after. May be he would feel more responsible and do something.

Please don't get me wrong, I love him so much, but the whole family is under lot of stress due to this. 

Please any advise, thank you so much!