PTO denied but I’m not coming into work anyway

My family has a trip planned that will require me take off 1.5 days. I put in the request in March for this June trip and initially without looking at the PTO calendar my boss said “sure that should work”. My entire family got the time approved and booked the trip. She then told me too many people (2 people) in the company region are off that day, but since our store has been particularly slow lately she might be able to make it work but she wouldn’t know until a week before. So I held out hope until this week and she told me there’s no way for it to work. By the way, I’m an overachieving employee that bends over backward any chance I get to help the company. This family vacation is already booked. My family and I discussed it and we think I should just tell her “I won’t be in these days. We talk about a work/life balance all the time and this is it. When it comes between work or time with family, family will always win. I am willing to accept whatever disciplinary action is appropriate, but I will not be coming into work those days.”

Thoughts?