I'm really glad you told an adult you trust.
A couple years ago, someone very close to me went through a lot of issues, to the point where that person could have been in super serious danger. Someone this person knew from school told the school, and they, in turn, told my family.
The person who had issues was super angry at first, but now they have a much better life, and things are going great for them.
I know that right now, you may feel like you betrayed your friend, by telling an adult about her issues. But in the long run, she may be grateful that you did.