You can try blocking.
It was doable on the old facebook chat by creating a list for that one person ..
aw are you kidding?? this sucks!
it's not doable with the new chat now , is it ?
just chat through messages, it works just as well and you can be offline.
Clever. Clever indeed.
You can do that now! With the new facebook chat. That's the only thing good about it. Just go on facebook and click on the little settings wheel icon thing at the top of the sidebar (they moved it to the top) and then go to "limit availability"
sweet thanks man