On my way home now I managed to do the unthinkable, I topped off the tank with diesel. Had about 40 liters of petrol in it and topped it with 16 liters of diesel. Drove almost 10 miles from the station to my house. It just hit me right before I parked, checked the receipt and what do you know, it says diesel.   After some reading it seems that petrol in a diesel car is really bad, but diesel in a petrol car is not as bad, and if I'm lucky I only have to change a few things after draining it.