After the initial shock, Naruto could become determined to prove his innocence if that was the case. He's a fighter, and he wouldn't just let this false accusation or betrayal stand. He might set out on a journey to find the truth and clear his name, all while struggling with the pain of his friends' actions.
Danzo could also be the main antagonist. He is known for his underhanded methods and distrust of anyone with too much power. Since Naruto has the power of the Nine - Tails, Danzo might spread lies within Team 7 to make them think Naruto is a danger, causing them to betray him.
It could be that the whole Team 7 is brainwashed by an evil ninja with powerful genjutsu abilities. They are made to believe that Naruto is the key to a great evil that will destroy the ninja world. As a result, they turn on Naruto, and he has to fight not only his former teammates but also the false accusations and the real threat behind the brainwashing.
At first, Naruto would be extremely hurt. He has always considered Team 7 as his family, so their betrayal would be a huge blow. He might go into a state of shock and disbelief.
One possible plot could be that Team 7 is manipulated by a powerful enemy. Maybe Orochimaru manages to cast a powerful genjutsu on them, making them believe Naruto has turned evil. So they turn against him. It could also be that they are forced to choose between Naruto and the safety of the village in some extreme situation and they wrongly choose to sacrifice Naruto.
Naruto would probably be extremely hurt and confused at first. He would try to talk to his teammates, to understand why they are doing this. He might plead with them, asking them to remember their past together. But when he realizes they won't listen, he could become angry. Naruto has a strong will, so he would likely decide to prove his innocence on his own, vowing to show Team 7 that they are wrong.
He could also get angry. Naruto has a strong sense of justice and loyalty. So, being betrayed might fuel his anger, and he could set out to prove his innocence on his own. He might go on a journey to find evidence that clears his name and also to become stronger so that he can face his former teammates if they become enemies. He might also start to rely more on other friends outside of Team 7, like Shikamaru or Rock Lee, who might believe in him from the start.
At first, Naruto would likely be shocked. He has always been so loyal to his team, and this sudden betrayal would be a huge blow. He might stand there in disbelief, unable to process what's happening.
Naruto's reaction could be complex. He might be sad and disappointed, but he also has a lot of love in his heart. He could try to forgive his teammates, believing that there must be some misunderstanding. However, if they continue to oppose him, his reaction would turn more towards self - preservation and growth. He would focus on his own development, both as a ninja and as a person. He would use this betrayal as a motivation to become stronger, all while still hoping that one day he can reconcile with Team 7.
One possible reason could be a misunderstanding. Maybe there was some false information spread about Naruto that made Team 7 believe he had done something unforgivable. For example, if an enemy framed Naruto for attacking the village secretly, and Team 7 fell for it without proper investigation.