How to move on from my Ex?

So me and my Ex had been together for 2 and a half years. Throughout all our relationship, She's been the one doing everything to me. She claimed to stop 'loving' me. She cheated on me. When our 2 yr olew relationship....I"m afraid to take the next step because I still deeply love my Ex. Even when my she talks to other guys I get REALLY jealous. I know it's not good cause we're no longer together but I can't d son was only a month old, she broke up with me saying she didn't "love" me anymore...and we haven't been together since then.. We're still not together but I still give her money to support our child. I know this isn't all much relevant but I've always loved her and always told her till this day but she's never felt that way with me ever since we broke up. The breakup occurred back in January of 2009 and the way I felt about her hasn't changed since then. Don't get me wrong, I've talked with a few girls within that time period but it never fails at the end of the day it's my Ex that's always on my mind. Even when I try to move on and I'm talking to somebody else in which it could spark up a brand new relationship...I'm afraid to take it to the next level cause at the end of the day, I still love and feel for my my Ex-girlfriend. Their have been times when she's came over and we've cuddled a little bit in my bed watching a movie and I'd always think to myself "This is how I want it." ...You know, having that feeling where you feel whole and complete. When she talks to other guys, I get REALLY jealous...I know it's not good and I shouldn't be getting mad but I can't help it. The only innocent one is my little son. I've always wished we could've been a family together but that was thrown out the window. Trust me I've heard it all from "You need to move on" to "You need to get with someone" but it just doesn't faze me at all. How can I move on? I'm literally losing my mind right now. The girl I once knew is gone and that' something I gotta accept. But how? That's where I turn to you guys....What can I do or what DO I do?