She needs to learn that Mommy isn't always going to get her out of trouble, in my opinion, you should leave her in there and make her face the consequences. If you take her out, you've already told her that she can do what she wants and you'll be there to help her (which is what she's going to think).
Let her lose her license for a few years, see how much she misses it, and see if she still wants to drive drunk afterwards.
As for her boyfriend, you could take him to court, but I doubt you would get anywhere. Without any evidence of him actually saying that, or any evidence that he ever slept with her you basically have no case. It can't serve as a confession either because he wasn't under arrest and didn't have legal counsel present. So don't waste your time with him
You should let her know that she is on here own in this world, and that actions have consequences, otherwise she's going to keep getting drunk, keep dating older men, and keep getting into trouble with the law. If you teach her a lesson now, while you have the upper hand, it may help her later on in life. Other wise, you're ******.