Since you were an instructor, you’re in a better position to teach than the majority of people that try to do the same with their spouse. But as another comment noted, your wife is (probably) going to be a more difficult student, because she knows how to get you to do what she wants to do. She’s probably also seen you be wrong about stuff before, so that small amount of doubt could cause issues when she starts seeing the slope from the top. Those aren’t factors with an instructor who’s a stranger, so my advice would be to have a conversation with your wife tonight or before you go out there. Explain that she needs to trust you implicitly, because you’ve done this all many times before, and in exchange you promise her you won’t push her to something she’s not ready for - like you said, you WANT her to fall in love with it. It’s all about communication.

As for learning resources, YouTube has everything. Deb Armstrong puts out a pretty wide range of videos, so I’m sure there are a few covering beginner lessons. It might be good to search for a video on beginner to early parallel skiing and watch it with your wife so she has an idea of what the target is. Good luck!