I agree that you did the best thing for your son...as well as the rest of the family, including you. I'm appalled that he got so violent with you and the kids. Especially being as big as he is - what bullying!
I've never been through the situation that you are in so I can't offer first hand advice. I can only imagine how twisted your heart must feel. I'm sorry you all went through that, and continue to be disturbed by the memory.
You did the right thing - both in protecting yourself and your family, and in doing all you can do to help him by having him leave. Because he would not have improved staying there, with everything taken care of for him. He wouldn't have been motivated to change - why would he, he was getting taken care of? I can only imagine how hard this must be for you. I'm sorry. Sending you hugs.
Please continue to post here. There is a lot of compassion, experience, and good advice to be found here. It will help you work through your feelings, and give you insight into the mind of those who are alcoholics/addicts.
Wishing you and your family the best, including your son.
Peace.