Why would they sue me?

I was involved in a minor accident with someone else, basically I was stopped, tried to change lanes didn't see the other person coming in the lane I was merging into and she ran into me. No damage to my car and very little to hers which gives you an idea of how minor the accident was. Anyway the person that ran into me suffered a small cut on her head and injured her toe or so she claims. I have insurance about 25k in bodily injury. Now my insurance company is telling me that this chick has gotten a lawyer and is looking for cash. My question is if the injuries were minimal to both her and her car why would she go to the trouble to get a lawyer and sue me? I have very little money, and it doesn't seem to make sense. Does this happen often do people these days sue just because they can. Do I need to get a lawyer as well? I am very stressed over this I didn't mean to hit this person and now it seems she is taking advantage of the situation and I am gonna get screwed.Why would they sue me?
If you receive papers showing that she has filed in court you should get an attorney, you may be able to counter sue for failure to reduce speed to avoid an accident since she hit you from the rear. if your car insurance paid for the damage on her vehicle and any medical expenses then she does not have grounds for a suit.~