How To Get Over It:
First, demand that the driver take you the direct route to wherever you're going... which you should, hopefully, have on your phone. If they won't listen, then get out at the very next stop, as long as the area looks safe. Having been in the back seat of a taxi that has other intentions, I can promise you that your best bet is to get out as soon as possible. Whether you hail another cab or walk, is your call. Just don't stay in a car where things are shady.