I kind of have imaginary friends, but I write fiction in my spare time, so I call them characters and write about them. When I'm alone, I often imagine conversations with them or between them, and sometimes they help me work out my own problems. They are real people to me, and when I discuss them with others (only other writers--other people just think I'm crazy) I talk about them like they're real. When I was a kid, I made up these same "characters" but I usually drew them or made them out of clay instead of wrote about them. I also played with dolls into my teen years. I was a pretty lonely kid, and I've turned into a semi-lonely 20-year-old, though I don't think I'm seriously ill.

Maybe you should see if you can use your imaginary friends in an artistic way, like writing or drawing them out. Even if you're no good at these things--and trust me, I'm no good at these things--it helps to get them out of your brain and into some kind of physical existence. It's quite therapeutic to be able to express yourself.