water damage

[billolive]

I live in and own a condo in California. My airconditioner leaked water into the neighbor's unit below ours. This caused damage to the ceiling and walls. The leak was called to our attention by the neighbor after she returned from a 3 month medical absence. Since we did not know that this leak had occured we could not do anything to mitigate the damage which occured over the 3 month period. We do not have insurance and the neighbor insits we pay for the repair to her property. Are we liable for this repair?