Trouble after an accident

Hello, I have a bit of trouble after an accident. I can tell you the facts you can give tips. I helped a neighbor with the corn harvest in autumn. I drove his tug with trailer. Everything so well. Around late afternoon I drove to the next field with us in the village. The road is not exactly the best, but stop two lanes with little traffic. I drove towards the field. From a distance I saw where I had to go. I reduced the speed because oncoming traffic came. S Put the turn signal on the left, but then waited briefly and thought if I was going to the field or directly to the next. I decided to drive to the field and drove off. Exactly at that moment a car overtakes me and patrols my left front wheel. Car left side broken, tugs no sheep recognizable. Police came, we described the facts. Police looked if Blinker was ok, then everything was kept on protocol. I did not really look into the mirror, the Autof I paid my warning money and thought everything was good. Today I got mail from the local court to pay for his car. The good gentleman was on his way with Papa’s car, probably told the insurance I didn’t want to be blinked or made signs. They don’t want to pay now. According to the court the testimony is available as proof and the police file. From this I would clearly be guilty and should have the time value Only I know exactly what was on the record and I also had a witness with me. Will you talk to our neighbor later or tomorrow, if he also got mail or what he knows about it, he is also the owner. Did someone ever have such a case? Or what do you think about it?