I'm sexually attracted to my uncle. (NSFW I guess)

First of all, so sorry for the throwaway, but I don't want to take the risk of him or anybody else finding out about this. I'm really ashamed and disappointed in myself. I'll put a tl;dr if anyone thinks this is too long. My uncle is in his mid-40's and married. He has 2 step sons and one biological son from a previous relationship. I'm a 15 year old girl. I've only known him for about a year because of family issues. My mom didn't want me to be associated with them so I just lived with her and my older brother and sister but they've been gone for like 3 years now. Life was pretty easy until we suddenly got to know the family because that's when I met my uncle and it messed me up. I was instantly attracted to him and have thought about him all the time since I first met him. Usually the thoughts are sexual. I just don't know what to do. I know it's wrong but sometimes I don't care and I continue to fantasize about him. I can't really help myself. I know he's married but I'm afraid that if given a chance I could totally ruin our relationship and the relationship with his wife by trying to make a pass at him. I mean, I love him to death, so it really makes me upset sometimes that I fantasize about doing things with him that would make him a pedophile. I haven't told anyone this and don't plan to. I just needed to let all this stuff out that's been building up in my head. tl;dr: I'm 15, he's in his mid-40's, and I want to have sex with him. :/