How about I say that I made some interesting imaginary friends and my boyfriend totally believes it!
What do you mean you made some imaginary friends? Is this some kind of joke?
I made them to humor my boyfriend.
Tell your boyfriend that he shouldn't take your imaginary friends seriously. It is an unhealthy thing to do at his age.
I'm in control here and I'm going to run my own world
You can deal in fantasy up to an extent, but to make the boyfriend seem to buy into it is not going to help his mentality. Please make him aware how it is just for play and not real. He will need therapy if you don't do that.