I would choose new friends. They aren't or he is not a friend. I'm not sure why you would even be in that situation.
I didn't like when my roommate would bring around "random" friends of his, and ask me to smoke them out. I still did it... But very little material. I wouldn't want friends to bring around other friends, who simply mooched. This was part of my frustration with him. I moved out.
But I wouldn't have some guy "watch my shit", who I worked with, and treat them as you have been treated. No matter the extra relationship otherwise, or not. That guy sounds like a fucking sack.
Boo him.
If he smoked with you no problem before, I'd wonder what happened to change this? Do you know? Was it like that? Simply not like you?
For me, I have been left out before, but usually by only one person in a group. Another would pass it my way. That person to skip me just made it unnecessarily awkward. I was usually with weed anyways, as I smoke alone a lot anyways. I have no issue keeping everyone happy that I can, but there has to be a real relationship for that to continue. If there is not, I'll find a way to not be around those people.
Are you alone basically in this town?
This brings me to the thoughts that I often used to get... If it weren't for the drugs and their unavailability, at times, I would not have association with certain people.