I see people who aren't really there?

I see people who don't exist like they have never been born I see them walk around my house and I think I know that no one else sees them, I can't tell who is real and who doesn't exist anymore when I'm outside of my house. When I'm talking to someone friends of mine will ask me who I'm talking to and then again I don't know if there real. What the **** is wrong with me, I never knew they weren't real until my mom noticed me talking to myself and took me to a shrink.