If you haven't yet, remove the cup and see how badly the threads are buggered up, you just might be able to salvage it. If not, find yourself a well equipped shop or a frame builder who has the Park tool for the job - here's the article from their website: http://www.parktool.com/repair/readhowto.asp?id=97. Good luck and don't feel too bad, sooner or later, anyone who does anything is going to mess up.