Strange dream, help with interpretation.?

I had a really strange dream, I was walking with my girlfriend somewhere halfway between my apartment and my ex girlfriends apartment. And there we meet with my ex, who doesn't even know my girlfriend...and they start to talk like they are best friends. All 3 of us were going towards high school and when we came to a street crossing we crossed and my ex got hit by a buss ( kinda like Regina George in Mean Girls ) and my and my gf kept going like nothing happened...What do you think it means? :))