There are a few of us older types here on this site. Personally I'm 69.
I wouldn't say that marrying someone older is necessarily a mistake, I'm 10 years older than my husband and we couldn't have been happier together. We've been married for 32 years now. So I doubt it is merely the age difference that is the problem in your relationship. That being said, it isn't really a magic topic so I'll stop with it here.