Sixteen is too young for him to be kicked out of the house. Is it at all possible for him to have his own room? I think the main focus should be towards him becoming independent and being a “mensch”. Perhaps he could go to school or learn a trade. Maybe by the time he is eighteen he will be in the army so he will be out of the house. Not that the army is so great but it’s better than being on the streets.
Write or wrong, I know exactly what you are going through. It’s a real hell on earth. I don’t know if you can afford it but it would be good for you to have a therapist to talk to. Try to take a little vacation with your husband and get away from this stress. There are so many parents that are just like you, going through the same thing. You are for sure not alone (not that it makes it any less painful). It is not your fault.
I think that us parents who have kids who are OTD go through a mourning process. We had this dream that we would have children and they would be frum and get married and you would have these cute little grandchildren. Then you wake up to a nightmare. and you mourn your dream but then you face the reality that things could be much worse.
I am wondering how your other children are coping with this. It must be very hard for them too.
Anyways I hope things get better very soon. Hang in there and don’t let it consume you, remember to take breaks for yourself and your husband. hatzlocha!