That's why I would not initiate new position 45mins before close. I would try to wind down 30 mins before close. This policy applies to both lunch close and day close. You can get a good ride and would want to hold longer, you can jump into a sucker rally/tank at close, but generally I would try to avoid the excitment.
My heart goes out to I have had a similar type of situation (Its a long story) but basically had to sweat being short, and unable to do anything for a week. Of course it cost me money. Basically its a shit one!
Using the estimate he gave in his original post, if he got out at the open, he suffered around a $10k loss. Definately not something to make fun of. My condolences on your loss. I suffered a large loss myself Monday night with the STW contract due to my own folly (got caught short in that parabolic upmove, didn't have a stop in the book, compounded the problem by getting stubborn and averaging in). I'm feeling the pain right now, and I it sucks. I guess the only thing we can do is learn from our mistakes and make adjustments to our strategies to make sure they don't happen again.
The best way to avoid fill uncertainty is to use Market Orders. http://elitetrader.com/vb/showthread.php?s=&postid=1679930&highlight=market+orders#post1679930