If I've followed the trail accurately, this is the security bulletin which describes the security risk which this update addressed: http://technet.microsoft.com/en-us/secu ... n/MS12-078
Note where it says:
An attacker would have to convince users to visit the website, typically by getting them to click a link in an email message that takes them to the attacker's website.
As long as you follow safe internet practices, and otherwise have adequate firewall, anti-virus, and other anti-malware programs activated and protecting your computer(s), I would say that you'll be safe until MS puts out a patch (or whatever they call it), if you were to uninstall the update. I don't know how much time passed between the time this possible route of attack was identified, and the update came out. But if you were to uninstall the update, you would be at no more risk than you were in that time. If you don't ever open suspicious email, or follow suspicious links, you should be fine. (Not that I'm a security expert.)
Or if you share a computer, you could uninstall the update, and just disable your internet connection until the work is finished, and you've reinstalled the update.
But, as PT said, your work is not lost. You should be able to open in any other program (which is not affected by this issue) and see all the missing text. Although this sounds like it affects a fairly broad range of products, so it might be hard to find one that's unaffected.
I suspect that MS is furiously working to correct the problem, but I have no idea how long that could take.