I.i.n to want to have sex w/your non-blood related uncle?

Well, I'm asking you guys this and I kinda want your guys' advice. My name is Crystal and my mom divorced my dad. Now she has a boyfriend of 8 years. Well a couple of years ago, I met my mom's boyfriend's BROTHER (Javier). I instantly fell for him. When i met him he was married and only had one kid. We would flirt and this and that. I would always go to his house. When he talked to me i would get butterflies, my heart would race, and I would blush nonstop. The first time he did anything to me (more than just touching) was in 2008. We were at my house with the family and I was sitting in the dark and he came inside, then he told me to go with him. I just sat there, and he came up to me and licked/bit my lips then he went outside. I flew out of my chair thinking that i was having a dream. I looked in the mirror and there was a line from where he bite me. From then on we would make out and touch but I would never let it go farther. Now he has 2 kids and is still married, But we still come really close to have sex. My sexual desires for him are through the roof. He has said he wants to do it but i always decline him. I dont know what it is but having sex with him is all i think about then when there is a opportunity to do so i chicken out. But then things got really screwed up. My mom found out i like him (when im really in love with him) I told her "yeah i do like Javier but its just like a normal middle school crush." But it WAS NOT. It was WAY WAY WAY WAY more. Now I'm deciding weather to have sex with him, Or just talking to him about whats going on and what he REALLY wants to do. I just want to know if its normal to think of him like i do. He really leads me on but then i think he is just using me. (13 year age difference) << I personally think age is just a number. I.I.N?!!!???!!!?!