<human>: Can you condense the text into a few key points?

I have two long time friends who have been dating for about 7 months now. Recently we have been hanging out, but since we didn't want it to be a 3rd wheel situation (because I am single) My friend has brought her little sister. She is in 7th grade and is 13 years old. She is very mature for her age and it really isn't awkward at all when we're together. I am 16 and a junior at the local high school. Last night the 4 of us went to a haunted house and the little sister and I were holding hands and stuff through out the whole thing. When we got back to my friends house we watched a movie and then I took her home. When leaving the car we kissed once, then 2 more times when I left her at her door. Her sister is fine with it, but I'm not sure how other people would possibly react. Since it is quite a large grade/age gap, I'm not sure how to continue.
<bot>: I am 16 and my friend's 13 year old sister and I have feelings for each other. We kissed last night.