How can you separate reality from hallucinations?

So, I have been trying to deal with my drug problem, and I was wondering, is there a way to tell the difference from hallucinations and reality? (Don't say, "don't do drugs" because yeah, I know.)

But anyone who was taken diphenhydramine (benadryl) knows how real all of the hallucinations are. Last night, I was lying on the couch watching tv, while my mom and her friend were looking at jewelry in the kitchen, only to find out that her friend was never over at the house.

Then, my mom was sitting on a chair in the living room, not moving at all. I am not sure if that was real or not. I am confused to what happened at all last night. Any thoughts?