My best friends are becoming stoners, do I really need the stay friends with them?
Is that a part of a larger problem?
Yes, I don't think I like to be around them anymore and also it's for my health related
I understand the way you feel. Your friends are starting to go down the path of using drugs and it's making you uncomfortable. If you no longer want to be in that setting, I think you're fine to leave them.
It's going downhill and I think we're done.
Seeing how much that it's mentally affecting you now makes me think even more that the best thing for you is to leave them. I'd recommend going out there and finding new friends.