You are still the primary on the loan, just continue paying the note. If you default, that is when a cosigner becomes primary and the law becomes tricky.
Currently, you are both equally liable to pay the auto loan. When your boyfriend files bankruptcy, the discharge removes his obligation to pay the auto loan.
I am assuming that your boyfriend is also on the title for the car. The only way this *might* impact you is if there's equity in the car that he can't protect. This is usually not the case, as most people are upside down, but it's something to look into.
Assuming this isn't the case, and there's nothing unusual with his filing, such as a vehicle redemption, then you shouldn't be impacted. Just make sure the loan stays current, as it will continue to report on your credit report.