Give her the time and space, but prepare yourself
If you love her and want to be with her, you need to give her the time and space to make up her mind.
Discussion Isn't Helping
Bringing it up for discussion doesn't seem to be getting anywhere and only makes her pull away more. So, be kind and supportive, but don't focus all of your energy on her and how she's feeling today.
Be Your Own Person
It's time for you to draw on your own support system and be your own person. Decide what you need to do for yourself. Other than your relationship, what and who make you happy? Spend some time doing things on your own. You need this for your own personal growth and you'll really need this if you end up splitting with your wife.
Get A Lawyer
I also advise you to make sure that your finances are in order. Does part of her "preparation" to leave you involve changing the bank accounts or putting big ticket items such as the house or car in her name only? Consult a lawyer (or at least a friend whose been through a divorce) to discuss the possibilities. You don't want to end up like Marla Maples, who got shortchanged by Donald Trump.
Things May Work Out
There isn't a marriage I know that hasn't gone through ups and downs, so don't give up yet. If you have as much going for you as you say, things may work out.