Since you didnt roll attack/damage rolls out of spoiler, it wasnt an offensive spell, only 2 possibilities: the STR buffing spell or the true strike spell. dont remember any non offensive spells you have besides these 2.
Hmm...even if it could kill me, no. If your readied action is shoot magic missile if he comes into LOE (assuming from effects), then that happens during my turn, and now it is your turn.
Never mind, it is your decision to kick yourself in the head.