We are all sorry you are here but you will get plenty of support. As aliveandkicking has said your story is pretty much script for most of us here, and I personally have never known pain like it.
Read as much as you can, find other threads like yours particularly on the Newcomers Forums, it will help you gain some insight and support.
I am in the same boat as you seperated from my children, in my case my W is divorcing me without counselling, fast tracking as quickly as possible to a new life in the home I built. New clothes, new haircut, new man, selfish to the point where she (and all other WAS's) re-write history to justify their actions). Not thinking about the children, only what they want, thinking the grass will be greener on the other side.
AK, just try to think about you and your boys at the moment. They will need all the support you can give them at this time, try and forget about your W at the moment, give her the space to think things through. DO NOT talk about your R, write down some things you can talk about before you go around to the house.
Keep posting, there will always be somebody that will respond.
Bomb dropped: 19/12/08 Me:48 WAW:41 D:10 S:6 Married: 15 years