Head´s up against loose all-in maniac(?)

[elcarlos]

Hey. I'm pretty new to poker but picked up some books by Phil Gordon and such.

It got me pretty far in a homegame tournament.

Head's up with the last contender I was being killed though. My opponent kept setting me all-in or folding. Folding about 25% of the time, and setting me all-in about 75%. I was folding and waiting for the premium hand since she was taking so much risk, but we were each down to 7.5BB at this point and she was taking all my blinds. The total chips in play were 15BB. In the end I called an all-in and was busted out with a K-7 where I was holding Q-8s or something.

What's the optimal strategy to play a person like this?