I am so confused, why does he hurt me like this?

My best mate does drugs and stuff. Some of my friends think he likes me but he treats me like a good friend only, he will never do anything to disrespect our friendship or me. He's very nice to me, and I really care about him. I wanna tell him I like him but I don't know how he would take it, he may not even like me that way. He doesn't like me having boyfriends, just wants me to stay single. But if i told him i like him it may get to him even more that we will never be able to be together due to religious reasons and he might start doing drugs again. It worries me. however, when i wanna talk to him or text him to see how he's doing he always tells me that he's getting drunk or stoned. Anything to do with that sort of stuff, it's all he tells me he's doing. Just a few minutes ago i text him and he told me he was buying weed at that moment, it almost killed me. Doesn't he realise how much it gets to me cuz i really care about him? What is he waiting for that he is continuously hurting me like this? Always telling me he's killing himself slowly, Why? What does it mean?