I cannot go back! The time it screwed up the quest ist 120 hours away from my current savegame, so I have to wait till it is fixed with a patch!
You probably aren't going to like hearing this but when this bug is patched it most likely will not fix the situation for people who have already run into the problem and then saved their game and kept playing anyway. Most quest bug fixes are going to be preventative in nature so that they prevent the bug from ever coming up in the first place. It's virtually impossible to code something that can dig through millions of unique saved games and rewrite them properly without screwing up other saved stuff.
General rule of gaming you just learned the hard way - if you run into a bug, first thing you do is reload a save from before said bug and try again. If that doesn't work then reload and try to figure a way around the bug. If that still doesn't work then reload the save from before the bug came up and then avoid that part of the game until it's been patched and then try again.
I'd say probably 90% of the quest bugs that have been reported in this game will only be fixed to prevent them from happening initially. There are only some that will be fixable even if they've already been triggered (probably things like already having a quest item in your possession, stuff like that).