I have gone through so many of the same things you have - and feel like you do - not wanting a divorce wtih a husband that just wants out. They think the grass is greener on the other side. My husband is cheating on me, though, with a kid half his age and sees nothing wrong with it - denies it, even.
I would absolutely get a lawyer - you need to protect yourself and your kids. There is one thing I know - you can't change another person - thier actions or behavior - or thier mind. I have often thought the best thing might be for my husband to leave to see what he will be missing. I have heard many times when they leave, they ended up regretting it.
My best advice - advice that was given to me is take care of yourself and your kids and stop spending so much time and energy on trying to make him change - it will never happen unless he wants to. Please try to get legal advice ASAP - most courts have a Family Center where you can go for help, if you can't get a lawyer for yourself. What he did to you, just to serve you papers like that - that is the act of a coward. Someone who doesn't have enough guys to tell you what he was doing.
Good luck. TAke care of yourself and your kids.
Me:36 H:38 Together: 20 years Married: 16 years Kids: 13 & 10 yr. old Discovered affair: 1/10 H denies affair. Refuses to save marraige. Divorce filed: December 2010