What to do when i'm getting sued?

I got into a car accident that was my fault about a year ago. Yesterday i received a court summon in the mail saying I am being sued for her injuries. I remember correctly, that i was the one with more damage, could not get out the car without any assistance and she was the first one to get out of the car. I remember her being angry and telling the cops she was not injured in any way. I am 19 years old and being sued with 25,000 dollars. What should i do?