That is terrible. I feel badly for you and the buyer and hope you can work things out. Hopefully its only the glass and cleaning up the mess. That broke like plate glass though didn't it? Everytime I have seen tempered break it shattered into pieces.
Think positive....at least they did not put a fork lift through it as happened so another pinsider some time ago. STI might lose some customers over this. I have never heard of them before.