My boyfriend has been lying to me! What do I do?

[L]

the relationship could be toxic. i know you like him and probably want to give him another chance, but you deserve better than that! a relationship is based upon trust, if you don't have trust, you don't have anything.
think of it this way-
if you marry him one day and want to start a family, and he's going behind your back to smoke/drink, what example is he setting for the kids? and the emotional toll it would take on you, why put yourself through that? or what if overdoses, say he starts using drugs. then you are left to raise children on your own.
i know this is hard, but i think you need you move on. if you don't, i think you may be in for a world of hurt.
i wish the best for you, i really do. you will get through this, it just takes time