That's a bummer about the misload - it can't have done your confidence on your first ever competition lift. I think with the misload and dropping like a stone, it was always going to be tough to keep balance.
Well done for a bench press PB in competition, and you nearly had the deadlift.
Try not to be dispirited that you didn't get the numbers you hoped for. It's still an experience and it takes a certain amount of bottle to go and lift in front of judges and an audience.
500/363/573 @ 220 belt only