Divorce is probable; what can I expect the future to be like?

I'm 49 years old and been married for 23 years; we have 2 children (21 & 16); my wife decided 6 months ago that she's tired of being married, and she's thinking of filing for divorce. Her father's health is ailing, and I think her selfish mother is instigating all of this because she will need someone to take care of her when he dies. My mother-in-law has always used my wife because she knows my wife won't tell her "No" for anything. Over the years, she's had my wife attend 2 of her class reunions, alone; attend funerals and weddings for her, and she continues to have my wife run errands for her all the time. I've been super good to my wife for the past 6 months in an attempt to change her mind, only to have her continually treat me like crap. I can't help but to try, because I still love her, and I love my family, and I don't believe in divorce, unless there is a major reason for it. She moved in with a girlfriend a week or so ago, but she still comes home for sex. Last night when she was here I asked her to spend the night so we could try to work things out, but she wouldn't. I told her I was going to get my own apartment, and she's telling me it would cost us money for me to move out, and she already has a free place to stay. I don't like staying in this house because it's a little too cluttered for me, and she doesn't want me to get rid of things (she has always kept lots of stuff). She's a school teacher, and now she tells me she will be losing her job due to cutbacks. If things don't work out between us, which is a likely scenario, what can I expect the future to be like? Will it be difficult to find another partner in life at 50 years old? Will I be broke because my wife will soon be unemployed, and the courts will force me to support 2 households? I've always wanted what's best for my children, and I know this isn't it, but I don't know where to go from here. Thanks for any advice.