Hey Shana-
Well, we can't undo the past. It's such a pat thing to say but it's true. Regrets are the past coming back to hurt us again in the present. Your dad made bad alcoholic choices - driving with children in the car is horrible. But you know what? Google it - it happens all the time. I'm serious. He's not the only person who let alcohol warp his judgement and you need to understand that DWI was not considered as serious in the past as it is now. Awareness was low.
That does not excuse him at all but you need to try to let that specific thing go because he can't make it up to you, he can't change what he did and you'll never really get any kind of satisfaction. Keep working on it with your therapist.
The sexual issue is beyond my ability to address. Please talk to the therapist about it more.
You can't control what happens to the bulimic friend. It's very codependant to let her problems drive you to distraction. She's not yours to worry about - she has her people. Worry about you hon - it's early in the semester and you have loads of time to work out whatever academic problems you are having.
Here's the crux - focus on you. You are important. Your education is vital. The way to help everyone else is to take care of yourself.
When you find yourself thinking about these upsetting things physically stop and make yourself think about something else - like your next paper due.
Take care of you. No one else can do it right.