i am tired of constantly comforting my friend

I (17F) have a friend (17M). We have been friends for 4 years now, but previously we weren't close, last year (2024) we got closer. He has intense body dysmorphia and constantly feels like other are judging him and hate him. He also has imposter syndrome and sometimes even harms himself because of it. Now we are both in our last year of high school, and i have science and he has humanities. So it is obvious that he has alot more free time than me. I have coachings and extra curricular activities and everything.

So my problem is, he texts me whenever he feels down and I comfort him. I take alot of time to text him paragraphs upon paragraphs comforting him and sometimes even call him for hours when im unable to type. But there is no improvement. A few hours later i will again receive a text saying that he feels weird in his skin, he wants to kill himself etc etc. Since the beginning of 2025 the amount of normal conversations I've had with him are like 5 and the amount of times I have comforted him are more than 20.

I use so much of my time comforting him that it is draining me out now. I dont wanna talk to him anymore because I know that someway or the other I will end up comforting him only.

what should I do?