My response:
Okay, I realize he's your friend, and I realize you're not too thrilled with the fact that a lawsuit has been filed against your friend.
However, you need to realize a couple of things and, hopefully, these will ease your mind somewhat - -
1. You were a negligent-free passenger.
2. The fact is, you were injured.
3. Naming your friend in a lawsuit is necessary, and really amounts to a "formality" of law.
4. Your friend will be defended by his insurance company at no further costs to your friend.
5. You are, in fact, entitled to have your medical costs paid, and to obtain money for your pain, suffering, and inconvenience of having gone to the doctor for treatment. The money will be paid by his insurance company - - nothing will come out of your friend's pocket.
6. This is why your friend has insurance. It's there to cover him, and to cover you, and others, for HIS negligence.
7. You can justify the lawsuit by asking yourself this question - - "But for his negligence, would I have been hurt and caused to seek medical attention?" If the answer is "No", then you're doing the right thing for yourself.
8. In less than a year, you'll get a settlement, and this whole matter will be a distant, and forgettable, bad dream. Your friendship will survive - - I guarantee it.
So, cooperate completely with your attorney and "ride the wave" - - it'll all be over sooner than you think.
Good luck to you.
IAAL