zeroxxx: I sympathize with your situation.
Wouldn't it be better to just... drop all those weird substances altogether? It's not like you're gonna die if you drop them all suddenly.
Go check with a doc or something for medication? I doubt it's not cureable.
Hard drugs (heroine etc) and alcohol withdrawal - cold turkey way - can indeed be fatal, because those are neuro-toxic substances. Your heart might go into an arrest, or your lungs stop working.
Neuro-toxic means that functioning of your nervous system is altered by consumption. Weed is addictive, for example, by habit and pleasure - but quite innocent physically.
Snus or snuff is only nicotine, as far as I know - but also nicotine is neuro-toxic, meaning that the habit is very hard to kick, because your nervous system has altered and expects it.
Medication might help some, proper clinical help some more - but hopefully human bonds are there too.