When you write from a place of utter calm. When you can regard your STB former spouse with indifference and dis-interest, you have achieved a place of peace and strength. If the two of you can negotiate a divorce together, that takes into account the needs of your child, then I think that you are doing very well indeed.
FWIT, my XH (1st marriage, this is my 2nd) and I, once we came to the realization that we needed to divorce, very calmly and openly discussed what each of us needed, how we wanted to proceed, and did our own property split together. Our lawyer basically just advised us what paperwork we needed to file and then represented us in front of the judge. If you can manage to do this, to split up your marriage with the least amount of fuss, money, and stress, then I think that you're doing much better than most.