We don't get a Hollywood ending, folks. Deborah isn't all better.
But Deborah is an admitted work in progress, so it's a good, honest ending.
Deborah has earned her GED and has decided to celebrate by looking at the high school kids in town doing their high school thing on the high school grounds. But when she sees them, and in particular a young couple holding hands and nuzzling each other, she gets upset. She thinks that no matter how hard she tries, the stigma she'll carry for fighting mental illness will prevent anyone from loving her like that.
This is also when we get the last showdown between Yr and Earth. The gods of Yr try to convince Deborah one last time to stay with them, because she'll never find friends like them or love like theirs on Earth. Deborah can feel the Pit coming, and she walks to the hospital, where she can have an epic panic attack in the safety of a cold-sheet pack and medical supervision.
And so she does.
When she regains consciousness, she decides to say goodbye to Yr at last. She sides with the world and decides to hang with it with her "full weight." This means she's going to give getting well everything she has. She's willing to try for what Dr. Fried promised her, which is the challenge to fight for what she wants and for the freedom to choose her way in the world.
We'll count this a happy ending in our book.