I'm so sorry you are going through this. As many have said in response to your post, many of us have had to do the same thing. Before weighing in on your actions, though, I have some questions. How old is your son? Did he have any warning that you might do this? Will you be there for him and help him if he asks to get into a rehab program, and if so, does he know this? What is his DOC?
One of the responsive posts alluded to this, but your motivation in asking him to leave should be to preserve your own sanity and happiness, not to make him hit bottom so that he will recover. I say that because the latter event might never happen. Or it might. How he responds to your actions is beyond your control. You should also be aware that the worst might happen. The stress and misery and humiliation of being thrown out of his home by his own parents may well trigger more drug use, at least at the outset, and he could OD. Or not, but it's possible, and you should be prepared for that possibility.
My AS was in in-patient rehab twice in a two-month period, relapsing within 48 hours each time he was released. The second time, we moved him directly into an SLE from the rehab facility, and he still relapsed and was thrown out of the SLE. I let him stay with me for four days to get clean so that he could go back to the SLE, but he used every time my back was turned. When the SLE wouldn't let him return because he was high, I told him that he couldn't stay at my house any longer. That was the last time I saw him. Two days later, he was murdered. He would not have been in the place and circumstance that resulted in his death if I had let him stay with me those two nights.
From a co-dependence and addiction recovery standpoint, I did the exact right thing by sending him out into the night that fateful day. But (and fellow board members, please don't pillory me for this bit of naked honesty) I wish I hadn't. I wish I had been weak. It breaks my heart to think that my last communication with him was my sending him away to fend for himself, the misery that that caused him, and then he was gone. No opportunity for one last hug, or for things to get better.
You probably did the exact right thing in throwing your son out of your house. I probably did, too. But you should be prepared for the possible (and hopefully very unlikely) consequences.
You and your son are in my prayers.