Is this CRAZY for a WIFE and MOTHER to do?

Not at all. The only way you would be selfish is if you were taking the money to go to New York, if it was needed for your kids (like if they needed braces now!). But you said money isn't the issue, you are a hardworking mom, I'm sure and you deserve to take this trip alone. I have always wanted to go to San Francisco, alone. And next summer, I am. My husband is okay with it. I think you feel bad because you don't want to feel as if you are leaving your kids and husband to go frolic in New York. But that's not the case. I think you should definitely take this opportunity. It's a once in a lifetime chance, and we aren't going to be around forever. Stop overthinking it and just go do it! You'll feel great once you have that accomplishment underneath your belt. It's a great feeling. You aren't being selfish in any way, nor are you being crazy.