Yes it goes through his auto insurance unless you have insurance in your name, if you have your own insurance then that would cover you even if you weren't in your own car. If you were not officially on his policy it would go through as host insurance meaning you have $250k of medical benefits from his policy. If you are officially on the policy then the medical benefits would be whatever the policy states, which has a minimum of $15k. Either way you are fully covered and should go straight away to the ER and let them decide what treatment/studies you need.

Also report the accident to your boyfriend's policy so you have a claim number and can get the process started. The insurance will cover you for any subsequent needed medical care, therapy, studies, and even medications.