From my perspective, that is a perfectly valid life purpose. I have one of those short, all encompassing life purposes, but I would have been just as happy (and I have to admit, a bit relieved) if I had found one that wasn't quite so broad in scope as *everybody*.
A life purpose is extremely personal, so nobody else can say whether it is right or wrong. Your purpose, which I can't paraphrase nearly as eloquently as you wrote it, is yours alone to do with what you will. If you want to expand it, and recognize that there are women out there who are in restrictive relationships who you could help empower, then that is right. If you want to keep the original wording, and make your wife the best loved person you know, then that is right as well.
As for world changing, in your eighteen years of marraige, surely you've seen the power of an empowered woman at least once... It is truly an amazing thing. If you don't think that a well supported and loved woman can change the world, well, you're about to see an amazing lesson.
One last thing to add. Do not be worried if your purpose was created from your guilt, worry about the changes that it will bring for the future. My purpose is based on a lot of guilt (the full story is at
askTrina.com » Blog Archive » Why ), primarily from a couple of points while I was a soldier in the U.S. Army. If your past experiences can help to bring a positive change, then don't worry about the past, worry about the changes that you can make today.