Being in recovery for many years (and also having lived with addicts and drunks) I can tell you that threats and ultimatums don't work. Boundaries, that are appropriate, are the best way to deal with it - always give choices such as "you can chew if you wish but I am going over to my mothers because I can't bear to deal with it". It is also appropriate to share your feelings but don't be accusitory or threatening. I would also find a support group such as alanon for yourself to understand the mechanisms of addiction and help for yourself.

Addiction is a tough nut to crack. I saw many persons sneaking cigarettes in the radiation treatment facility at UCSFCCC (which is one of the leading antismoking research facilities in the world).