I feel like the world's meanest teacher

I think I kind of screwed up. I didn't do anything technically wrong, but maybe I should have considered the consequences a bit more carefully.

I had my students hand in an assignment one week before the end of the teaching period. I pulled out all the stops to get it marked in time to return it on the last day of class, so that the students can use the feedback in revising for the final exam. Except... I also have a policy that I don't accept late work after it has been discussed in class—even if said student was not IN class that day—because they might have heard the solutions from someone else, or seen them on WebCT in some cases. Bear in mind that these are problem sets we are talking about, not essays. There are right and wrong answers. This no-late-work-after-discussion-in-class policy is clearly stated on the syllabus and on WebCT. It is also a policy that is generally shared by most courses in my department.

I warned students in class the week before last that I would be returning the assignments this week, although I forgot to explicitly remind them this mean they couldn't hand them in after Monday.

Approximately a third of the class was more than one week late in handing in the assignment. I didn't realise how prevalent the problem was until I had already returned the first class's sets, and already told some students that no, I would not accept any more late work. Now my inbox is full of 20 or so begging emails explaining that they are so incredibly sorry, they had no idea they couldn't be late, since when does a lecturer return stuff with a week's turnaround anyway? and now they aren't going to graduate and it's all! my! fault! Except that it's all! their! fault! and they won't do it again, promise, just please please bend the rules this one time or my mother is going to kill me.

I really really don't think I can change my policy now, because some of the students affected dropped the course, and if I bend the rules for others then they dropped for no good reason and would have every reason to be pissed off with me and maybe lay a complaint. As it stands, I don't think anyone has grounds to officially complain, but I am possibly going to have the highest fail rate of any course in my department, and a lot of miserable students.

I have offered alternative assessment to anyone who, after the final, sits on a mark between 40 and 50% and was affected by the late assignment problem. This isn't much different from official university policy anyway, which requires me to offer make-up work to students sitting on a mark between 45 and 50%. But I don't know how many of them will take me up on it. Mostly I think they'll just sulk and fail.

And it's all! my! fault!