My boyfriend at the time hit another car in an intersection. It was my car and my insurance. I got a call today saying that a lawsuit might be filed against me. What is my liability here? I wasn't even the driver! How much can they try to take?
One passenger was taken away in an ambulance but did not have any visible injuries.

It is your car, and your insurance, what part of your liablity don't you understand. They can sue your boyfiend as the driver, and the owner of the car.

So of course they can sue you.

If this was your boyfriends fault, they can sue for all the damages to their car, all the injuries at the doctor any loss of work and so on.
If your insurance has just paid them, no problem, but it appears your insurance has refused to pay and so they how have to sue you.