Minecraft - Fell through the bottom of the map...Am i ******? please help.?

I was digging with my instamine mod on, and my diamond armor (-9999 damage(invins) lol got tired of playing legitmatly) and i broke the bedrock, and fell through the bottom of the map. It wont let me die. I've tried removing my invincible armor, but it wont kill me. what do i do?