It is best, of course, to persuade you to see a psychotherapist. Not a psychiatrist or a free clinic, but a private psychotherapist if there is such an opportunity (first of all, we are talking about financial opportunities and whether there is a chance to persuade your friend to at least try therapy).
If there is no such possibility at all, perhaps you should try not to convince her that everything is fine and she is beautiful, but try to understand what exactly causes her so much pain. You can ask her to tell her about your problems, but at the same time, firstly, act gently (if you do not want to share, you should not press, it is better to postpone the conversation until the best moment), and secondly, show understanding and not try to convince her that her problems are not serious.
I looked into your profile and saw a question about hand scars. In my personal experience, a depressed person is much less willing to communicate with a person who is not experiencing or has not experienced the same. You can try to tell her your story, but here you also need to act carefully, do not dump everything at once. In no case should you convince her that your problems are more serious (they say, "if I coped with my problems, then yours are generally bullshit"), but it can be useful to share the experience of how you got out of this state and what helped.
This is a rather slippery topic, but it might make sense to talk to someone from her family. Slippery - because anxiety can be false, and you can permanently lose its trust, and relatives can decide that this time the alarm is false, it means that it just wants attention (people are different, without knowing in advance it is difficult to say what conclusions a person will make) ... And then there will be no one to help her when she really needs it. Therefore, on account of this point, it depends very much on the situation, but as a way to save a person, you always need to keep in mind. However, here it also depends on relatives, if you know them well enough and there is a way to convey the problem to them so that they do not act harshly and thoughtlessly, then you can try, perhaps they will help with finding / paying for a therapist, for example.
Please note, I am not speaking from the position of a professional psychologist, but from the position of a person who himself experienced this (albeit slightly less acutely) and communicated closely with a sufficient number of people in depression. In any case, it is better to consult a qualified professional.
(I continue, because the question cannot consist of more than 160 characters) the worst thing is that she gets even worse from the fact that I say that she is always there, that I will always support, that I love and that she is beautiful. But as if it were pointless. As if she absolutely does not care and such treatment of me, as if I am to blame for something and she is offended. She talks about death every single day, I am scared to leave her alone. I don’t know what to do, because she can’t go to a psychiatrist either, because she’s doing a complete fuck in her studies, she’s stupidly no time.