“am afraid that this is what my life with her would be like”

Oh Honey, this is what you life is like. She is not going through a rough patch, this is how she runs her life.
As you said, she is not taking responsibility, she is not getting the outside help she needs.
You might see clearly the path she needs to go down, but you can not make that happen for her.
She is responsible for her happiness…now go be responsible for yours. You know this is not how you want to live.