OK, you are scaring yourself so STOP!! Calm down! I agree with your sister about the horror movies. It is not unusual IMO and doesn't mean she is going to be a deranged serial killer! I had an imaginary friend as a child, so did my sister who is 2 years older than me. It was something we used to construct games around when we were on our own or even together. It was fun!

I don't think having an imaginary friend is wrong or strange. After all, she knows this friend is imaginary, not real! It is just an outlet for when she is playing on her own. An imagination is a good thing IMO. She is only a child and it is one of her best assets. At least she isn't relying on the TV or video games to keep her amused.

Once you have calmed down, talk to her about it. Ask her to draw a picture of her friend. Ask questions about when does she play with it. Find out some info. That could ease your mind as well and will give you some additional info if you want to take it further.

I can't help you deal with it or give you any tips but if you are that worried, then talk to your GP about a referral to a psychologist.

However, breathe deep. You are a great mum so give yourself a break if you don't handle things in a perfect manner every time. There is no 'perfect' answer.