Tough luck, She shouldn't have mentioned your status. Now they know that you are here w/green card there is no way your sister will  EVER get F1 or tourist visa. They have everything on file so she can't deny you being here.  If she does deny the fact, she might get permanent ban. But again, getting F1 visa is a case of luck. IF she reapplies, the officer might overlook the fact that her sister has GC and grant her the visa but it would be going against the rule and the officer can get in trouble for doing that.

Better try UK or australia!