How do I comfort my cousin after board exam stress?

TW: exam stress / hopeless thoughts

My cousin sister recently gave her 12th board exams, and she told me a few days ago that she feels like she might fail her physics paper.

The thing is, I live in another state, so we don’t meet often. We usually call only 2–3 times a month, but when she said that, I could clearly feel that this is not just “exam stress” anymore. She has been talking in a very concerning way and I’m scared for her mental state.

I have been trying to console her again and again, telling her that one paper, one result, or one bad phase cannot decide her whole life, but I genuinely feel like my words are not reaching her properly. I am also thinking of going to her house in a few days just to be with her.

I honestly just want advice from people who have been through this, either personally or with someone close to them.

What should I say to her right now that might actually comfort her?

And also, to every student reading this, whether it is boards, entrance, NEET, JEE, CUET, college exams, or anything else:

please do not tie your whole worth to marks, ranks, or one exam.

I know it feels huge right now. I know it feels like the world will end if things don’t go the way you wanted. But trust me, your life is so much bigger than one result sheet.

You are still needed here.
You are still loved here.
And there is still a life waiting for you even after failure, disappointment, or a bad paper.

Please don’t keep everything inside.
Please talk to someone.
Please do not suffer alone.