If I am understanding this, your ex-husband and your current husbands ex-wife saw things in him that you were not ready to see and your ex attempted to remove his children from the situation but lost in court.
Now you are trying to save face by remaining in the same area with the same school to eliminate issues such as “I told you so” from your ex-husband?
I’ve always found that untangling the webs we’ve weaved with straight forward honesty always makes things work out.