Must I pay blood money to the family of my friend who died in the accident, knowing that I was following all correct traffic rules?

The answer can be summarized in two scenarios:

If the one who caused the accident hit your car, and it swerved due to the force of the impact without any action on your part, then you are not liable for anything. If the one who caused the accident forced you to swerve to avoid him, which resulted in you hitting the wall due to an action on your part, then this is considered accidental killing from you, and you are liable for the blood money (diyah) and expiation (kaffarah).