What do I do about him???!!!?

Okay so I have had a best friend since 6th grade. (We'll call her Sara) Sara and me are inseparable. She has a twin brother, even though they look nothing alike. (Call him Rick) He used to be so annoying to me, but during freshman year we also became friends. He has always been sweet and caring, and different things like that. I had starting liking him too, but I would have never said anything. During Valentine's Day he asked me out in Sophomore year. we broke up 6th month later. I am really independent, and all. He just got real clingy and followed me around at school. He said he wanted to walk me to class or to my car and I let him every so often but it got annoying. He was always a gentleman, but is a geek. (I am too but I don't like video game as much more of a TV buff and know-it-all.) He know me really we and doesn't mind that I a crazy and rambunctious, but I couldn't stand the constant texting or the facebook post about me or posting on my wall every day or his stupid statuses with quotes... uh... it made me sick. Anyway after we got over some awkwardness, it got better. We are back to being friends, but he flirts a lot. Really I do like him and now that I am a senior I can really see a future with him. I don't know though. I feel that if it does things will repeat. I spend the night over there all the time with his sister, and I might just be confused... Someone help here!!!