Ultimatums aren't always a bad thing if you are using them to take care of you and not to force change. If you are ready to leave unless he quits then there is nothing wrong with saying that...just don't say that thinking it will change his behavior because only he can do that.
If you are concerned for your safety you may want to do this in a public place and have a plan of where you will go afterwards.
You may also want to check out an Al-anon meeting in your area for support.
Sorry to hear of you troubles. ((hugs)) Take care and always remember SR is here to listen.