Advice on eating disorders

So I’ve been struggling with my weight for a while now I’m in a good place I’ve realised my best friend is developing bad habits and I don’t know how to be there for her, she just doesn’t listen to anything I say, she isn’t eating enough now because she’s scared to gain weight that she did last summer, and I’ve noticed she’s joined a group chat for people recovering from ED’s it makes me so sad that she is doing this and doesn’t feel like she can come to me, she said that she’s scared of calories I just want to be there for her and I’m getting more concerned now all she keeps doing is calling herself fat when this girl is literally perfect idk what to do