I agree with @tressygirl
Your comment on the feedback says a lot about you.
Personal comments about the buyer (which nobody reading your feedback can verify) may reflect poorly on you.
Nobody likes negative feedback.
Nobody thinks it is fair.
As soon as you got the feedback, you should have offered a return and refund. When the problem is resolved, you can send a feedback revision request although it is too late this time.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)