The good news tom is that you have before you an opportunity to have a great relationship with your kids mom. That doesn't always happen to people who go through what we have.
You have been doing this for long enough and are now able to open your heart to the possibility that you and ex can be friends. That is fantastic and just shows what a good man you are.
My aunt and uncle have been divorced for 20 years now. They are great friends and still do things together, with their new spouses even. They have a grandchild from my cousin and throw birthday parties together for him. They even have a christmas party together at my aunts house for the whole family. They are able to do this because each of them at some point after the divorce came to that place where they each owned their responsibility and were able to forgive each other and mend the hatred.
I am not saying that this is what you should do today, you are still fresh off the divorce, but to see the big picture and allow your heart to be open to this kind of relationship in the future is a huge step. I hope that someday I to will be in that place.
