Not only did my wife give you money, but so did my brother-in-law -- mostly because he's a big softy who recently had a dog pass.
I do not give a shit about the money, because it was not a lot, and because I frankly do not blame you for fundraising and for still going down to the game. Shit, I piss and moan about money bullshit too, and I went (sans tickets, but it was not a cheap weekend.) For my part I don't care. I'm not sure what I'm going to tell my brother-in-law, but hey, that's probably my wife's problem, not mine.
What I think you should be taking from all this is a serious thought. To wit: you wouldn't have this problem if your initial post had mentioned your trip.
Everyone here probably thinks it's a good thing if you don't have to choose between your dog and taking your son to the game. That includes me -- I'd have approved the same gift from my wife in a heartbeat. (Not that it matters -- she didn't wait for my approval.) Which means you'd probably have gotten about the same amount of money if you'd disclosed.
And you'd probably be getting a lot more sympathy now if your initial reaction had been "Oh, fuck, I didn't realize how this would come across. I did want to do both. I should have disclosed that I was making the trip. I'll refund any gifts you guys made if you want me to."