Hi Doodle, Glad to here your still in one bit.
Please do me a favour and bin your handle bars too. If they are bent then getting them back to normal will be risky, think of when you get a paper clip and you bend it, then bend it back to normal, it tends to snap. Can you trust your bars to hold up in an emergancy stop with all your upper body weight transfering through them?
As for the course of the miss hap, i can see yours and your partners theory just so we can narrow it down, know when you bump start a bike you normally have to run like fook to get it to bump, how fast was to coming up to the lights? also did you feel the back wheel lock up for a split second before it shot off?
Keep your chin up and get back on her (once you have replaced them bars tho!)