Already damaged MacBook Air charger suddenly stopped working

Recently my roughly-a-year old charger for my MacBook Air 11" 2013 tore near the magsafe connector, and by the time I fixed it the rubber protection had torn all the way around and frayed the wire inside, yet even though only the rubber inside was the only thing connected, It still worked and I was holding it together with tape and a rubber band. After about 3 weeks of that, Today a friend of mine was using the cable, It was working fine, but after he disconnected it, I was unable to get it to charge my own device. I tried using multiple different power plugs, and I know it is not the device (Which does need battery servicing) because another friends charger was working to power it. Can someone tell me what I should do with the charger? Up near the connector the rubber has separated all the way around and the wires inside are no longer touching, but the inner rubber piece and anything inside it is intact, it had been working like that for weeks but just gave in today. I have tried pushing it so that the inner wires touch, but that did not work. Can I get it working again? It is school issued and only needs to last me for 6 more weeks until the end of final term when the computer will be surrendered back to the school, What should I do?