As you have learned, your story is all too familiar.
The only advice I can give you is stay close to your kids and love them with all of your heart. Let them draw strength from a strong father who would do anything in the world for them and you draw strength from them without them even knowing it. I know that I do from my kids. When I'm really down and W is, seemingly, doing things to drive me purposely crazy, all I have to do is play with my wonderful kids who need me to be strong. I have never played so many video games, Barbies, monster trucks, board games, games of catch, flying kites, you name it. It has brought us closer together.
Weather or not my W and I ever reconcile, it won't change the closeness I have found with my kids. While she is out running around, they know who is taking care of them.