Re: Should we remain friends?
It is completely false that ex spouses have to be friends or even more than civil to each other. Sure, there will be school functions, graduations, weddings, births of grandkids, etc. None of that means you have to even so much as speak to her.
You can both arrange separate celebrations for birthdays and holidays. Parent-teacher conferences can be scheduled separately. For school plays, band concerts, sporting events, graduations, or whatever, you arrive separately, sit on opposite sides of the venue, and have no need to interact. When the grandkids come along, you go to the hospital to see the baby at different times. In all reality, it's not that hard to avoid other than the absolute bare minimum interaction with your ex.
Follow the evidence where it leads and question everything.