I cannot get over this man, 2 years and still strong as ever, feel at breaking point?

He'd think I'm a weirdo if he knew I said this, but I absolutely love him, when he flirts with people or I even see him write to another girl on facebook it hurts inside, I want him to be happy but I hate the girls he talks to, I feel like killing them. It's not fair. I'd be able to give him everything, I'd give up everything for him. I'm not bad looking(Without being big-headed) and hes not amazing looking, I'd say were from the same kind of looks area. But I don't focus on his looks, every other relationship/crush/fling I've had, I've focused on the looks of them, but with him it's like I don't even care. I know there's something there, if only he'd realize it. I know he never will. But I feel like I'm never ever going to get over him. I've tried so hard. I've dated other people trying to get over him and it doesn't work. I've know him since October 09, so near enough 2 years and I loved him honestly from the start. We started as good friends, but he liked and wanted me, but I was taken at the time and didn't want to cheat. Now I let my chance go, and 2 years on, he's not really bothered about me, he texts and talks to me from time to time, with suggestiveness and flirting, but it never goes anywhere, I feel like I will never move on from him, I'm stuck with this spell over me. I haven't had a relationship since october '10 and I just need somebody to love me more than ever, I've just recovered from anorexia and still struggling with depression and my anemia's got pretty bad. I just need someone to look after me, and be there for me and I feel like its MEANT to be, what am I supposed to do to get over this or just find happiness at least?