If your wife tells you want a divorce, in fact -- every time she brings UP the subject -- just simply say "I do not want a divorce." Or, "That's not what I want," or "I don't want to divorce you."
It will exasperate her, but you mustn't waver. Your position is twofold:
1) I love you and do not want a divorce;
2) I will not live in an "open" marriage, nor tolerate infidelity and disrespect from my wife.
You're simultaneously telling her that the current situation is not an option, but also that you don't want to end it. She needs to see you fighting for your marriage, so hopefully she will begin to do the same.
In my opinion, she doesn't believe you will fight for her.
