Lots of quite harsh replies here. I am going to go against the grain and say I feel rather sorry for your wife. I am almost the same age as her, and women's expectations about work, and the working world were a bit different than those of today, when we entered it. I work 20 hours and post-menopause, I feel a heck of a lot less energetic than I did fifteen years ago. Did you not anticipate any of these potential issues when you married someone twelve years your senior?
Do you mind me asking why you are posting here? To lessen your guilt? To hear people say YANBU? I understand you feel miserable and trapped currently but will seeing strangers on the Internet, who know nothing about your relationship, except your side of things, and what you have chosen to share here , say "yes leave her" really make you feel better about things?
I think it might be better to talk to your wife gently and honestly about how you feel about her and your relationship. Does she have any clue that you are thinking of leaving? Does she have any issues to do with self confidence or anxiety that stop her from working more? Does she need support to find work? She is obviously going to have to find more work whatever your decision.
Outside of "money and sex" what else do you BOTH bring to the relationship? I ask, not because those two things aren't very important, but because it seems quite a transactional way of describing a marriage of twenty-five years? You haven't really mentioned anything else about her.
Are you good friends?
Do you support one another?
Is there still respect and love and loyalty between you?
Do you do any of the housework & cooking?
Were you a good and involved father?
Has she been a good wife to you?
How do you think (honestly) she would describe you as a husband?
What would you miss about her if you separated and vice versa?
Good luck 