Yes you are. Or your insurer is. It is an offence to "knowingly" let someone else drive your vehicle without the provision of cover. If you acted in good faith and was told by your friend that she was covered to drive any other vehicle under her own policy then your insurer under the road traffic act will have to cover the third party claim against you.

It does depend on how the third party claims: If they are told that your "friend" was not insured, and no policy is in place, then they would seek to raise a claim with the MIB (motor insurance bureau) in this situation. It will not affect you. If the other party makes a claim against your insurer under the road traffic act, then your insurer could seek recovery of these costs "if you knowingly" allowed a person to use your vehicle whilst they were not insured to do so.

You would then have to sue your friend for these losses. If as above you acted in good faith, then your insurer may well go after your friend for these losses.