Sleepovers at Ex's House?

While we were in the stepkids' state for my ss graduation, sd asked if my oldest daughter could spend the night at her mom's house. After the VERY bad history (years of conflict) with the ex, there is no way we would say yes. I also would not have let my daughter drive an hour late at night with anybody else anyway, which was when she asked, to go to the ex's house...but spend the night at the ex's? I wouldn't give that woman ten minutes with any of my kids alone, let alone an entire night. 

Do your own kids spend the night at the ex's house? 

Wouldn't it be nice if for all those years, there was no hateful conflict and things could look so different now.