A childhood belief about imaginary friends

Oh let's see, when I was four, I had three imaginary friends, Frak, yes Frak, (my grandfather's name was Frank, my grandmother often yelled his name), and Joanie and Sandie, until my sister was born and then I left them at the hospital, locked up in the bathroom in my mom's hospital room. I was scared they were going to take my baby sister away. I kept looking out of the back window of the car, expecting to see them chasing us. I slept in my sister's room for a couple nights until my mom made me sleep in my own room. I was so certain they were gonna get her. I believed this forever.