Well.... I haven't exactly been in your shoes, but my husband and I were in divorce proceedings for 6 months.
There probably isn't anything you can tell your husband to change his mind or bring him "back." The only thing you can do is work on yourself, help your kids and try to create a great family environment.
The goal should be to make a great YOU and a wonderful family that any man would want to be with. Only by doing this is there a very small chance your husband will realize what a great thing he's losing.
Basically during my divorce I decided to focus on me. I tried to make me a better and more "attractive" (not just physically, but emotionally, attitude, etc..). I also worked on having a great home environement (calm, happy, positive kids, etc.. not easy when they are hurting from a dad leaving... but that became my focus). I also made sure to have time for me. Time to hang out with girlfriends, shop and do things for me. I began treating myself very well during the divorce.
I emotionally detached from my husband (look at detaching. There's information on this website and elsewhere on it). This allowed me to be friendly and even generous without expecting anything from him. I took the focus off me and convinced myself that if I did love this person (my husband), and he was unhappy with me, but happier elsewhere, I needed to let him go. By loving him I needed to support his decision to find happiness wherever it was. And for my children and myself I couldn't let this decision crush me. I needed to see it as a learning and growing experience for myself. I told him I wanted him to be happy and supported whatever decision he made. I also did mention that I believed he would be happier with me and the kids. I told him the "door was open" if he wanted to come back (before the divorce was finalized. After that I'd be gone), but I'm a wonderful, intelligent, beautiful women, and I have great kids so I'll have a great life wherever it takes me. I did try to make sure he realized he was losing something special... that was my words and attitude.
I also tried to slow down the divorce as much as possible to give him time to realize this.
It's kind of like setting a bird free. You let it go, and if it comes back it's meant to be.
Good luck to you.
There is no arriving, ever. It is all a continual becoming.
