Is it supposed to have damaged another car, hit-and-run?

Hello, I have a problem: 3 weeks ago I was parked in a public parking lot (please don’t go into it, since I know afterwards myself that I should have called the police..) In any case I touched the car next to me lightly while parking out narrowly, at the same time an elderly gentleman was at his car weirdly opposite me, and he saw this. He helped me to run out of the gap and when I wanted to see if I was looking at the car next to me. the old man drove away. I found nothing on the car and also my friend who was there saw nothing on the other car and also nothing on my car. I thought, lucky, only unfortunately I got a business letter from the police now 3 weeks later and I should report there, because it had come to a traffic accident escape! I looked at the foreign car again and in fact there is now a small dent on the driver side, ONLY that was there Not yet! Now I am accused of causing this dent, since the older gentleman has also seen that I have covered the car, but he has not made sure if there has been any damage, because he has just gone away! Is he a credible witness then? Will I still get an ad? What consequences will this have if I am still accused?I am afraid, because I don’t have much money as a student.