Well it happened and I'm sorry.
Is there any tech contact at Mt. Gox these days?
Please tell us why you sent so much and who did you think you were sending to?
I read this thread and part on Reddit and didn't see the answer (maybe I missed it) ...Sorry about your loss.
@DJFC
I was about to ask a similar question. I don't really think the amount is relevant though. What I mainly wonder about is: how precisely did you end up sending it to that address? If you had not sent anything there for a year, then how did you end up using that specific address? Did you use something like an address book and you clicked the wrong one, or did your wallet get compromised, or ..?
Note that I am asking this because I am sincerely interested in understanding the situation in detail. And I think it can be helpful to everyone here to understand what went wrong, in an effort to try and prevent the same mistake happening again.
In either case: I hope you manage to recover the funds.