The rest of his friends would probably gather around him, offering support and trying to cheer him up. They'd bring him water or whatever they thought might make him feel better. They'd also share stories to distract him from the pain, like the time they had an adventure together and overcame a difficult obstacle.
Boruto's reaction would be complex. He'd be heartbroken, for sure. He might start to question his own worth and purpose. But over time, he'd realize that he has to carry on Naruto's legacy. He'd become more serious and focused. He'd also become more empathetic towards others, understanding the weight of sacrifice. He might even start to study Naruto's techniques and leadership style more closely, trying to emulate the things that made Naruto such a great Hokage and hero.
His friends from Team 7, like Kakashi, would feel responsible for Naruto's situation. Kakashi would likely use his resources to find a proper shelter for Naruto. Shikamaru and the others might come together to form a sort of support group for Naruto. They would pool their resources, like money and food, and also try to cheer him up by sharing stories and jokes.
Sakura, being a medic - ninja, would likely be very concerned and immediately start trying to diagnose and treat Naruto. She might be constantly by his side, using her medical skills to ease his symptoms.
Sasuke, who has his own complex relationship with Naruto, would probably be in denial at first. He's seen Naruto as this strong - willed person, and the idea of him having schizophrenia would be hard to accept. But as time goes on, he would become more protective. He might train Naruto in ways to control his mind during the episodes, using his own experiences of mental discipline. As for Kakashi, he would be empathetic. He has his own traumas, and he would do his best to support Naruto, maybe sharing his own stories of dealing with difficult mental states.
There could also be friends who are so loyal to Naruto that they would consider following his request if they truly believe it's for the greater good. However, they would be deeply pained by it. Kakashi, for instance, might understand Naruto's selfless nature but would also struggle with the moral and emotional implications of taking his life.
In most 'Naruto gets sick' fanfics, his friends are very concerned. For example, Sakura will immediately start using her medical skills to diagnose and treat him. Sasuke, although he may not show it outwardly as much, will stay by Naruto's side and keep a watchful eye. Shikamaru might come up with plans to make Naruto more comfortable during his illness. And Hinata, she would be really worried and would probably bring Naruto some home - cooked food to help him regain his strength.
Sakura might be initially shocked and heartbroken. She has been Naruto's friend for a long time, and his sudden departure would leave a big hole in her life. She might try to convince him to stay at first.