Ouch! Take your time. I had a bad cycling accident (my own fault, no car involved) and had to be airlifted to a trauma center. I started riding a month later, and on my first commute to work, I was tapped by a car while crossing the street in a crosswalk with the walk signal. I decided that I could get freaked or that I could live as fully as possible, which for me meant riding my bike. I decided on the latter, although I'm super careful and ALWAYS wear my helmet, even if I just go around the block.

Take the time you need, and do what feels best to you. Get another helmet before you ride, though.