Jack,

You did the right thing by getting her immediate medical attention. Beyond that, while I feel for you and your situation, you're behind the eight ball in this matter. In most places, a fiancee has no legal rights or standing whatsoever.

The two medications you mentioned (and whatever else may have been found when they performed a tox-screening at the hospital) do not mix well. Methadone in particular is one of the worst to mess around with due to its long half-life and effect on certain cardiac arrhythmias.
Do Not Forget the Risks of Methadone in Pain Management

I am concerned that beyond immediate medical issues, there could be some legal ramifications for one—or both—of you further down the road. I don't think so, but I don't know for sure. I sincerely hope things do not go that way. I do think there will likely be some counseling/rehab at the very least.

In my experience, when bad things happen to a young person, two things very often happen. Parents go into denial that their child was at fault, and they desperately look for something—or someone—else to blame it on.

Just some things to keep in mind as your fiancee recovers.

For now, I'm not sure what you can do that you haven't. Folks here know what feeling powerless is like.

If you haven't been barred (threatened with arrest) from the hospital, I would just be there for her (as I know you are) every day. Make it known to her family and the hospital that you are. If you have been barred, write to her every day, and send it by (certified if you think you'll need proof) mail.

Until she is discharged, or asks about/for you specifically, I don't know of anything further you can do (though I'm sure we would both welcome any other suggestions).

I wish you both the best and happiness.

Doc