Hugs luco... my ex-bf was abusive in many ways, had problems with drugs, alcohol etc.. I knew that people don't just have those "problems" without reasons, which is what kept me with him for far longer than it should have.
You can't fix him and you don't have to feel guilty for that. There's nothing you can really do to make him "better" or more "honest". He has to change himself. And: he'll survive without you.

Btw, the straw that broke the camels back for me was that we met somewhere in public and he just couldn't stop "hopping/jumping" around. I asked him what he had used and he just said nothing (which obviously was a lie). We broke up that evening

take care...