Hunnie... we need to talk!
First, I would say that if she cares that little for your marriage, it is time to pick up that chin and talk to the lawyer. You need to live your life too! There's no way that anyone would see the person who is staying home, maintaining the bills, caring for the kids and striving to make it work as "the one who gave up".
Second, life is much too short to be miserable. Whether either one of you is in the right or the wrong, you have the right to find your own happiness as well. She's out finding hers, according to you, so she's obviously moved on.
Its not easy, its going to hurt like hell but in the end, what's worse? Staying in a miserable marriage or giving yourself the opportunity to find a bit of happiness while you are still on this planet?