Hi there, i feel your pain. My '93 Gibson Les Paul Std has also been knocked off a stand and fallen to the ground, resulting in pretty much the same break in the headstock as yours.
Please let me assure you with all my heart and in all honesty that this is a very common issue for angled-headstock guitars! I personally know of at least three or four other people who have had exactly the same neck damage due to the same cause - falling off a guitar stand, or being accidentally dropped on the ground. Your headstock fracture is quite standard, as far as headstock fractures go, and it looks like a fairly clean break so repairing it should be quite straightforward - if done by a professional luthier.
My Les Paul's headstock broke in 2003, and I only managed to get it fixed in 2004 because I couldn't find anyone I trusted to do the job. Since then, the guitar has played and performed flawlessly, and still sounds as good as ever! I've continued to string it up with 10s, with no problem at all. Even though it wasn't a very good repair job, it still worked very well and the repair has held up to this day.
My bandmate in Vertical Rush has also dropped his SG, resulting in the same broken headstock. I got him to send it to Malcolm Tan, and here is Malcolm's page detailing the repair job.
http://www.mtlutherie.com/fixes/repair_SGBrokenHead.htm
It was a really quick job, and my bandmate got the guitar back within days! It really plays as good as new, if not even better thanks to Malcolm's stellar setup (which was part of the job). And because he needed to use a guitar, I lent him my once-broken LP, just to show him that a guitar with a headstock repair is still as usable as a normal guitar.
I'll second Shredcow's recommendation and strongly urge you to contact Malcolm -
www.mtlutherie.com as he really is the best there is, and your guitar deserves nothing less than that.
Trust me, its not the end of the world, your guitar can be restored and be almost as good as new. Don't fret!
hope this cheers you up a bit.