Is it okay when your ex brings a date to school events?

We heard from a divorced mom who needs your advice after what happened at her kindergartner’s recent Back to School Night.
So, here’s what she told us:
“It was a bit upsetting to be there alone,” she says. “But then 15 minutes into it, my uninvolved ex-husband decides to show up with his girlfriend. OMG!”
“My [...]