Am I guilty for still wanting to go to prom despite our financial situation?

I am a highschooler with a moderate background, I cant say that we are poor, just blessed enough to make it around. My father makes good income, compared to other households, it can be considered high. But due to the construction of our other house, we had to skimp on money. Now prom is coming up and when I informed my parents abt it, they said it was up to me if I wanted to attend. At first I didnt want to but after a few days of contemplating I decided to attend. I didnt want to let regret crush me when I am older for not attending something that can make highschool memorable. I told my parents abt it and they agreed. Fast forward many days after, they suddenly brought it up again, saying if I really want to attend, I of course said yes. My mother was enthusiastic so I didnt think much of it until her sudden change about the situation. She started complaining that prices are going up and how she's stressed about our finances. I started feeling guilty, but I also felt wronged.

They were the ones saying it was up to me if I wanted to attend, and now they kept saying that it is too heavy for their pockets. I love my parents but sometimes they are a little bit insufferable. Or maybe I am at fault, that despite knowing our situation, I still wanted to attend.

Does anyone have any advices?