I know this is only going to further enrage you, but the Prosecutor likely offered up the dismissal without the defendant saying so much as a word, At least that's what transpired in my case. I literally signed in, then 5 minutes later Prosecutor dude walked up to me and says "Im dropping the charges due to the fact the witness (other party in the accident) didn't show up, your free to go"
Fact of the matter is Columbus DA's give absolutely zero fucks about Traffic crimes. Seriously, you'll be sitting in court with Crack heads that got busted stealing 40's of Old English from 711 sitting on your left, dudes that spent there last $20 on the bag of Heroin they are being charged with sitting on your right. These are the people the Prosecutors/Judges are there to deal. As I said in my own court-thread a few years back, Columbus DA's seem to do every last thing they can to get petty traffic offenses thrown out/dismissed as fast as possible.
That said, sounds like the Prosecutor made you a promise she likely didn't keep, nor had any intention of keeping. Now that is something id be extremely pissed off about. They swore an Oath to see Justice Served to the best of their control ("Justice" being a punishment that both of you see fit).
Not only did she fail to uphold Justice, she straight lied to you (or "gravely misspoke) in the process.
I'd file an official complaint. Prosecutors are held to much higher standards then your average Attorney and should never be pulling shit like that.