G.,
Been there and done that! My twins daughters were 18 months old when I got rid of the cheating SOB. It was a very difficult time. My daughters are now 10, I'm remarried and have a second set of twins b/g that are now 2.5 yrs old.
The most important thing I learned is that no matter what happens between you and your ex or how mad you get, NEVER let on to the kids. As far as they are concerned, their father "walks on water". Be as honest with them as you can without pointing fingers. Your boys will go through some rough times. Just make sure you reassure them that both you and your husband love them very much and that they are not in anyway responsible for your divorce. Your boys will be needy and will require a lot of extra time and attention from you. You, as a single Mom, will also go through some rough times (as I'm sure you are already aware). Be strong and enlist the help of friends and family. Make sure you still make time for yourself because you to too will feel needy and need time to heal. Put yourself and your boys first, everything else will fall into place. If your boys see you strong and happy, they will learn to be also.
Good luck to you.
M. H