Replacement veneers, teeth filed down by 2mm. Are they permanently damaged?

I recently cracked 1 porcelain veneer of the 6 that I have had for 30 years & decided to redo all 6. The new dentist "prepped" my teeth. I heard her say that she was filing the teeth by 2mm. In the middle of the procedure, she said, "These are vital teeth. Let's do an Xray." She didn't explain, but I thought this was odd. Basically, I'm terrified that too much is gone and my teeth are permanently damaged. Can you advise? There's more to explain but the site is allowing me only 500 words.