I seriously doubt your W is looking for you to "save" her from her actions. Personally, I think the best way you can "save" her is to establish the boundary of what you will not accept and that if she goes to OM, then she's made HER choice. It doesn't have to be YOUR choice.
If she goes on the trip and you have told her that it goes over your boundary and she rubs it in your face, then I would nicely pack her things up and leave them out in the driveway for her when she returns.
You mentioned that your financial sitch was harsh, so let her fend for herself. It's what she wanted any way right?
All you're doing is accepting what you want to accept.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.