OSF, I'm sorry it's come to this. That said, try to think forward (just a bit) to understand that it won't always be this bad, you won't always be so sad and heartbroken.
In the moment, it is all overwhelming, try to focus on the here and now when that happens. What needs to be done today (only). Call your friends, talk to your trusted family members, remember how important you are. You are very important to your family, your friends and to us!
It is sad when a person we care about can't get out from under the addiction. Maybe this will be a turn around for him too, maybe not, that's not predictable, the only thing that is predictable is that you will actually be better off, even though that probably 100% doesn't seem to be the case in the moment.
A plan to get away is a very good idea. I wouldn't worry too much about his name being on the lease or anything like that right now, except as it pertains to you. He will either refuse to leave or he won't, that is out of your control but you do need to be ready to act.