Let me give this a try. First you have absolutely no control over H. You can't make him come back no matter what you do unless he decides he wants to. H sees you right now as needy and clingy and he doesn't want any part of it. He feels like he already tried to make it work regardless of what you think. It's too late in their minds. They don't believe you'll change. All they can think about is themselves.
The only thing you really have control over is yourself. Thus, work on changing and improving yourself. Go out and GAL. Do things you enjoy and try (as hard as it may be) to have fun without H. Act Happy around H and don't let anything he does or says bother you. If you find yourself getting upset or in an arugument or heated discussion - leave or ask H to leave. Don't be at H beck and call either. Don't talk or contact him for a week or so for example. It's very hard to do, but you can do it.
It's hard to explain, but in a way, you need to try to go back and become the person you were when you first met. You didn't need him, but you had fun together and were a happy person. Seeing you like this again, can remind H of what/who he fell in love with.
My other input here though is that you have to let go of of the past also. You can't change the past, so let it go. Work on what you want to change, which is the future going forward. It's hard to let the past go, but you have to learn to put it behind you and not bring it up. Just work on what you can change - you self, and your future going forward.
Need2Believe
Me: 45 H: 49 Married - 21 years SD from H 1st M - 30 S - 14 S - 11 Asked for D - 8/14/06 Found out about OW - 8/30/06 Moved out 10/14/06 Moved back in 4/1/07