I think there are lots of great answers here about responsibility and ideal money management. However, I have a different view from many. You're 45 (which is young to me), extremely responsible and have been working hard toward your goal of no debt. I would take the vacation, which is not a frivolity but a celebration of accomplishment. I don't like the term "adult up", at least in your case, as it implies that it's irresponsible to choose this reward you've saved for over using that money to pay for an unexpected blip in your budget. Whichever choice you make, you've certainly 'adulted up' already and if you determine that this trip is more meaningful than a little bit longer wait to reach your debt-free goal, then it's really nobody else's call whether or not it's the best choice. You obviously understand the ramifications on your budget if you go, and at your age I don't see it as a problem.
I'm going to echo what someone else said earlier: life is not a given, and we don't know what's around the corner. I know plenty of people who have blown every paycheck and lived to regret it. I have also known many who carefully saved and paid off and waited for the day they had "earned" the right to go on a great trip, only to have something take away that ability. Of course there's a happy medium, and I feel you recognize that. If you feel this trip, whether as planned or in a scaled-back fashion, is the best use of the money you've saved, then go on the trip without regrets and revise your budget accordingly.