I Am Unhappily Married

I have been with my "wife" for 25 years.  Now we have nothing in common, hardly even speak to each other and basically live separate lives in the same house.  I am sure that I could completely disappear and that as long as my paycheck kept landing in the bank account she wouldn't even notice.  I know that I have not been perfect, far from it, but as I am getting older it is just hard to imagine spending the rest of my life with someone who couldn't care less about me.  I am so lonely that I can hardly stand it anymore, I don't have any friends, and I'm pretty sure that there is someone else in the picture again, a repeating pattern so I recognize the signs.  I don't have any idea how to get out and meet someone, or how to end this misery.  I have tried to talk this over, and my feelings are always minimized, I'm whiney, I'm wrong, I'm weak, I never want to do anything, the list of the things that are wrong with me is virtually endless.  I want to believe that there is someone out there who could love me, I am educated, have a good job, reasonably attractive, at least I am not homely,