What on earth am I supposed to decide?

My boyfriend got into a car wreck on the way to college today. When he got to school, this girl I went to high school with asked him if he needed a ride home. He said no, but only after I tearfully begged him not to ride with her. I hate the girl and I know she's a lying, manipulative little tramp. Anyway, after we got home, we had a huge discussion about our choices for the both of us getting rides until we get a new car, and his only option is to carpool with her. I trust him, but he's hurt me before. He keeps things from me. and he didn't tell me she had his number until after she called him, about 7 hours after he'd been home from school. He had 7 hours to tell me, but he didn't. He hid this from me again. So now what do I do? No one else from our area goes up that way to St. Louis and I have no answers. Do I trust him? Even after today?