My husband is 16 years younger than I am. We met at work, my divorce from 1st husband had just been finalized and he had just left a committed relationship. We clicked as friends immediately, but the age difference was a big stumbling block to anything more. We got a lot of negative feedback from co-workers and family about our friendship, so it took over a year of being best friends before we were willing to take the relationship further.
At first I got a lot of questions like: "is he your son?" But mentally and emotionally our ages meet somewhere in the middle and to us it's just a number. My DH has always been "old" for his age, much more mature than others of the same age, and I have my immature moments so it works. We've been together for 15 years and married for 8. Sometimes it surprises us both that it's been that long.
Many times we both wish we could've been closer in age, but we were meant for each other, so we just accept it. I get a lot of responses like "you go girl" from women who have never met him, but people who know us just accept us for ourselves. And, yes, there is definitely a double standard on May/December couples. It's fine for an older man and younger woman, but every one has a negative opinion about both people in a relationship where the woman is much older, and feel compelled to tell you about it. LOL But it works for us and we've been together so long that we don't get much of that anymore, either.
My in-laws were understandably disappointed at first (the no grandchildren thing), but they were very good to me and my children and now accept them as grandchildren. They were way better than I expected, and I will always be grateful for that. In fact they accepted me far sooner than my family accepted him. But it's all water under the bridge now.
Ultimately no one can ever know what works for other people, or what will work for you in the future, you just have to know yourself and go with your heart.