Seems like a difficult time to be starting something new, when you're still dealing with the fallout of your husband's cheating (I'd assume that's not completely resolved after so little time??). I'd probably hold off if I were you, you don't want her to get sucked into any drama. That said...
Things I would ask:
- Normal date questions (where'd you grow up, what do you like, etc.)
- Relationship orientation questions (have you done poly before, what are you looking for out of poly, do you have an ideal relationship configuration in mind or do you just let things happen as they happen, are you looking for poly-fidelity or an open model, etc.)
- Emotional resilience questions (would you say you get jealous easily, do you need to hear from people you're involved with every day in order to feel happy and secure, etc.)
- Lack of experience (obviously everyone has to start somewhere, but poly is Relationships 201, so to speak)
- Issues with jealousy/insecurity, etc.
- General flakiness/craziness
Another big red flag from the other end of things would be if your husband is going to try to push this into being a situation where she's involved with both of you, rather than let her figure out what she'd like (just you, just him, some combination thereof) herself. I mean, I'm sorry, but that guy kind of seems like he's more than happy to manipulate situations to get what he wants......
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.