thanks SIL!
for anyone reading this who might be in a similar situation, WORD TO THE WISE... i found out that if you don't take any one of the legs of your ticket (or any leg for that matter) any other flights on that ticket (including for example your return ticket home on another day/week) will ALSO be cancelled.
this is for "security reasons" and i think new, or at least more strictly enforced now. you have to be reticketed, which involves a change fee, which may or may not be worth it.