Imaginary friends! PLEASE HELP!?

Ok so PLEASE ANSWER if you relate... Since I was about 8 or 9 I have pretended people exist, even though they don't. An example. I pretend there is a boy in my class. He has a name, an age, a date of birth, I can imagine his face. I make up who his friends are (other real people in my class). I make up his adress, his parents names, his siblings names, his pets names, etc. And I pretend he is real a lot of the time. Although I know he isn't real, and I never think he's real (I'm not crazy). But I just pretend he is and pretend it to myself. I have never told anyone. It's like an imaginary friend, but I actually pretend they're real, and not just for fun. And I can't seem to stop doing it (like it's addicting). It dosen't have any negative impacts on my life, but sometimes I'm scared it will make me crazy, if I know someone who has the same thing it will make me feel much better. And the boy in my class was an example, it can be a family member, a neighbor, a celebrity. I just pretend they exist in the real world. So please, does anybody feel the same? Or know somebody who feels the same? Or has maybe seen a documentary on it or anything? Please I am desperate! By the way I'm a 16 year old boy! So yeah that's it... PLEASE HELP! Thank you :)