Yeah, Pru is right here: as hard as it is, LW, bite your tongue, get a therapist, and just be there for your daughter. Her girlfriend is going to prison soon. That will absolutely remove her from influencing your daughter, especially while COVID is a thing, because she'll get to budget her outside contacts. (LW doesn't mention whether the girlfriend is 18 or if she's going to juvie, I note.) This will likely be a shocking chapter in daughter's life, but girlfriend will go away soon enough, and teenagers have problems with object permanence when something is not in their face all the time (as do we all). Daughter will move on, go to college, get a life.

You cannot rescue her, LW. You can, however, be there to catch her if she stumbles or asks for help, and to model the life she can have if she stays the course. She's probably going to talk more to her siblings about all this since you've already tried to talk her out of things. Suck it up, you already screwed up, all you can do is try to remediate your own response and hang out.