If this was a teaching situation with my son and I, I would say this.
"If it were me, I would be apologizing for to my friends and family in this case. I would say to them, 'I understand that you were helping me when I thought I wasn't in a position to help myself. I sincerely appreciate that and I messed up. I found that when given another opportunity that I was able to come up with an approach to pay for a trip to Miami for my son and I. I could have used that money towards the dog. You sacrificed for me and I find that I didn't myself in this case. I'm going to do what I can to pay you back. I am sorry.'
"Now, you have to learn to make your own decisions and live with the consequences of those decisions. You can do what you want, but please remember that your decisions impact others as well."
Of course, my B9 is incredibly rational and makes cost benefit / opportunity cost decisions all the time, so this probably would not take place.