I found out recently that my ex-but-still-best-friend relapsed. A friend of mine saw him smoking weed the other day and he's posted pics of him smoking from a pipe on FB. And I know some people don't see a problem with tobacco and marijuana usage, but I do. And it makes me sad. I'm thinking about talking to him or writing him a letter or something to say how I feel, in a loving, non-judgmental, and yet honest way. And he's a very strong Christian, so he knows better but I think he's just fallen again. I really want him to get better. Am I overreacting? And what can I do?