MiSoberbio

Just remain focused on your life, your joy, and don't allow him to invade -- that's what he's doing: invading you, trying to blur the line between you and him so that you become an accomplice in his illness.

From my own experience and from what I've heard from many others, it's a very common technique for an addict to try to confuse the loved ones in his or her life, especially by making said persons doubtful of their own sanity... It's hard to understand, but an addict is focused entirely on consuming substances. The substance is loved, the substance is worshiped, and everything else is inconsequential, to the point that everything is lost. Family, friends, possessions, clothes, health, teeth, internal organs -- eventually, everything is lost. Here in Argentina I often hear that addiction is "an illness of loss" and I see it happening with my companion (who remains in the streets).

So, your friend is trying to bring you along on his ride into hell. It's your choice if you want to go there.