i was driving another persons

i was driving another persons car and got into a little accident into my parkinglot at school. it was nothing big just a little bump when i was pulling out of my space. the other car was driving behind me. the owner of the vehicle gave me her insurance card and it said she was covered from the beginning of that particular month. when the other party tried to call the insurance company to collect the company said that the policy was not in effect. this was a fill in the blank temporary card, so i didnt understand why they would fill out a card for the vehicle and then not cover. well the other party's insurance company is trying to collect from me. i called the local police dept. and they told me that unless i was issued a ticket at the time of the accident stating that i was at fault, then it is the owner of the vehicles responsibility to pay. well as it turns out the police were never called to the accident and i was issued no ticket. i just want to get some further info. on this if someone can help. Thank you, yvonne