I agree, I loved this scene as well and it was something Haley needed. Talking to someone she knew very well and was really close to her, did very little for Haley at the time. Nathan, Jamie, Quinn, Brooke... No one managed to get to her because they were people she knew very well and had a bond with. I believe in situations like these, hearing someone you barely know sharing details about similar experiences really makes you think about it because at the end of the day, I'm sure Haley thought Nathan, Quinn, Brooke and everyone else close to her were telling her those things (ie that everything would be okay and that she was strong to get through that) because they loved her and wanted her to get better, it didn't necessarily mean those things were true. But hearing those same things from Victoria, someone she barely interacted with, she didn't think the same thing. Victoria telling her the things she did because she loved and cared about her wasn't an option so maybe, just maybe everything Victoria and everyone else told her was actually true and maybe she could really get better. And she did.
At least that's how I looked at it.