What should you do now?

Your answer to slow down and drive as far to the right as possible is correct.

According to German traffic rules, when a faster vehicle approaches from behind and wants to overtake, you must facilitate this by reducing your speed if safe to do so and by positioning your vehicle as far to the right side of your lane as possible. This helps create enough space for the overtaking vehicle to pass safely and smoothly.

Stopping is not required and would actually impede traffic flow and could be dangerous. Maintaining a steady and predictable course while allowing the overtaking vehicle to pass is important for safety on roads, especially rural roads where space is narrower.

In summary, slowing down and moving to the right side supports safe and efficient overtaking maneuvers according to German driving laws.