Falling off a roller coaster?

Ok so i had this dream last night and it scared the crap outta me. i've never had a falling dream before and im scared of hieghts..but here it goes. i was on a roller coaster with my brother and my cousin. the roller coaster wasn't going up or down just level and it was like in the wilderness. like a train i guess you could say but when it started turning at a bridge i felt the wheels slide and i yelled "we almost fell off see?!" then before i know it the thing just flew off the bridge! we were just falling and i could see the river below but it was really shallow and i just remember thinking im gonna die im gonna die and hearing my bones crack in my head and stuff and i was gonna yell i love you to my brother right before we hit the ground and i woke up. i never hit the ground though! ugh the worst dream i've ever had! what does that mean?? thanks anything is appreciated!