bb - you're so strong and full of wisdom. It's so hard, what you are struggling with, you and your kids.
You're lucky your FIL is there for you, that will help in the long run no matter how it turns out with H. Your kids will have a loving Gdad in their lives and that has to help.
The part about the kids pain. That is truly tough to deal with, however noone is better equipped as a loving Mom to do that than you. You're the best bb! It will be hard on them but they will grow up knowing what true love and committment is because of you. I saying this because I lived it like them and know its possible with a loving Mom like yourself.
You're strong and tough and you will make it, and you have those that love you so when you don't want to be strong or tough that day then they will be there for you all the way.