Thanks for voicing this fear Faith. I'm sure we've all felt this trepidation.
I'm wondering if the group has ideas to support how to effectively set the scene in order to feel more comfortable that you can ask more controversial discussion prompts. I think that even though controversy can be difficult, it could also lead to some pretty major 'aha' learning moments if handled well.
In the book, Design for How People Learn (by Julie Dirksen), she quotes Jonathan Haidt, who talks about the brain being like a rider and an elephant:
The rider is...conscious, controlled thought. The elephant, in contrast, is everything else. The elephant includes the gut feelings, visceral reactions, emotions, and intuitions that comprise much of the automatic system.
So Dirksen basically says that when designing learning we need to talk to the elephant to get learner's attention. (But I add on to this, we need to have some "rider control" in there somewhere so that students and faculty can feel and be safe in those discussions...)
One thing I could suggest is to do some sort of group agreements activity at the start of the course, having the group generate how they are going to work together and communicate with each other throughout the course.
Others may have more experience facilitating through conflict or controversy than I...does anyone else have something to offer up here?