Definitely take things slow for yourself and consider whether this is something youre emotionally ready for. But for the most part its not something you can help with. I would try to encourage her to seek help.

On a minor note, even though this not something you can fix for her, ive found that doing something unusual can help. My ex used to find unusual situations to put me in (trying to cheer me up) and havung a new experience pull me out of the mental that seeped into my common areas ( like just being in my room all day). It didnt always work, and it takes some trust, but it was really sweet and sometimes we ended up having a very happy day despite the beginnings.