Just an idea-if she won't talk, why don't you just do? Get the kids out of the house for a night, set up a scene for her, something you can be comfortable with (check with our Doms for some tips, like writing yourself a script/list of ideas to keep yourself on track) and go for it. Make sure she has a safe word, so she can stop things--using "red" for full stop and "yellow" for slow down/not this might be really helpful since you two haven't done this together before--and see how it goes. If you are really open minded, try talking to her Dom. Maybe he would be willing to share her, or at least some tips about her. And does he even know she is married and doing this with him without your okay? A lot of the Doms here would be really uncomfortable with that idea.
I know, a lot of info in a short space, but I hope some of it helps.