I would call your lfs first. This may be a chance for them to demonstrate excellent customer service. If it is a deep scratch I don't know if that is buff out- able, but perhaps glass experts know about some sort of resin (like how they fix chips in your windshield) that could help?
I'm sure you feel terrible about this, goodess knows I would. I hope there is a fix for this that doesn't cost an arm and a leg. If it is not feasible to fix it, then maybe it's just a chance to practice accepting imperfection.
Keep us posted on your progress!
- Ian