What should I do to clear my conscience before God after being involved in a car accident that resulted in a death, knowing that the deceased was driving against the flow of traffic?

Whoever kills a believer by mistake is absolved of the sin by two things: First, paying the blood money (diyah), which is borne by his 'aqilah (male relatives on his father's side) unless they pardon it, in which case it is waived. If he has no 'aqilah, then it is on him. Second, expiation (kaffarah), which is freeing a believing slave. If he cannot find one, then fasting for two consecutive months, based on the saying of Allah the Almighty: (And it is not for a believer to kill a believer except by mistake. And whoever kills a believer by mistake - then the freeing of a believing slave and a compensation payment presented to his family [is required] unless they give [it up as] charity. But if he was from a people hostile to you and he was a believer - then the freeing of a believing slave [is required]. And if he was from a people with whom you have a treaty - then a compensation payment presented to his family and the freeing of a believing slave. And whoever does not find [one or cannot afford one] - then a fast for two consecutive months as repentance to Allah. And ever is Allah Knowing and Wise.) [An-Nisa':92]. Accidental killing is when a person does something permissible for him, but it results in the death of an inviolable person. The killer is obliged to pay the blood money and expiation for directly causing the killing, and the victim's involvement in the cause of his killing has no effect on the ruling.