Well drink driving is a concern. I can totally related to the hypomanic state of mind that leads you to do it though so don't be too hard on yourself. It is best you are honest with your therapist so you can find ways to avoid getting in trouble. I still doubt hospitalisation is called for though.
Substance abuse goes hand in hand with bipolar. I have been there. It is tough to get out of. Hopefully your therapist can help you with this. is there anything you can think of that will help you not to get behind the wheel while drunk? Maybe you can put some barriers in the way, like giving your keys to someone else or catching cabs. Take care.