Wow, not sure where to start.
I'm a little confused about your wife's behavior. She views swinging as a way to keep you, but what about just opening up sexually together without the swinging. It seems like a last ditch effort. Of course it's difficult not knowing your situation beyond what you described. Advice I've seen over and over is that swinging will not fix basic problems in your relationship.
My opinion is that, regardless of the strength of the relationship, uneven rules are not the way to go.
Another thought is perhaps she is just so stressed out about the swinging situation she's just acting out to make it more difficult?
if I were in your situation I would not consider swinging. I realize it's something you had in the past but it's not something your current relationship can handle. You need to decide what is the price of keeping your marriage intact. If you two are on completely different planes when it comes to sex, then that needs to be dealt with. Numerous outcomes, you work it out and things get better; you try to work it out and it just does not get better..perhaps you stay together, perhaps not; or you continue as is and you may not be together as well.