Hi HeartSushi, have you checked out "Codependent no more" by Melody Beatty?? its a GREAT book... and you are not a bad person for placing your boundary.
When I was involved with someone toxic and suffering a lot, a woman that went by "GiveLove" wrote to me saying it hurt her to see me being so sad and allowing/creating many bad things for myself. Among all my confusion those words really got me and I started listening more closely, perhaps the same happens to your friend.
In any case you deserve your sleep and peace. Probably she learnt her role from parents/caregivers. You cannot change her history, that may be going on for generations. Its simply not in your power. And perhaps the mom already knows but is in denial. And you telling her, or anyone else, won't change anything either.... we always think there is a magic formula but it doesn't work that way... we each have our own path to walk as others have said...
PS Handing the people I love to God, HP, the Light of the Universe, etc, has given me much needed peace.