Tend to go the opposite way on this one.
Everything I read on the subject says you shouldn't tell the kids.
You may for your own sake tell them that you are not the one mainly at fault if things don't work out.
But remember she is still the mother of your children and they draw there self-esteem from both parents. Run down her you lower their self image too.
Its tough. Its unfair because this is one more time you are betrayed. But in the interest of the kids you need to disclose as little as you can.
I know how bad you want the kids to know its her fault.
We me and my wife were at our worst it felt like the entire world was blaming me kids included. All most people could see (kids included) was you being angry and her being depressed. Many wrongly assumed you hurt her....indeed in my wife's emotional state she often clung to me or even swung at me when I was trying to leave.
When I would "escape" her grip I had to literally pry her off of me. That resulted in grip bruises on her arms near her wrist. Her students saw her trying to cover them up and thought I WAS ABUSING HER!
Little did they know I had to document with our marriage counselor 9 fist size bruises on my shoulders where she belted me during one of her rages.
Not truly her fault she was unloading years of repressed sexual abuse along with the guilt of having been drawn into an affair.
But still it was tough not telling somebody-kids her boss who called me and so on--that she was the offending party not me.
In the end I am so glad I didn't because if I had it would have made reconcilation all the harder.
My story:
http://www.marriagebuilders.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=31;t=009539