Theory:

     No, no, she’s as old as I am,” says Akka. “That snap was taken when she was still in school. It is from her first movie.”
 
     Shree is angry with Akka, then stops to think. Is Chaitra using someone else’s picture— a film star’s? “How old are you?” she types.
 
     “I told you I’m thirteen, the same age as you,” Chaitra types back.
 
     Shree replies, “That is good. Best friends should be the same age.” “Hey, the earrings in your profile picture are so pretty!” types Shree.
 
     “Thanks, I made them myself.”
Explanation:
 
Shree was not ready to accept the fact that her aunt had told her. It may be because Shree can't seem to hold someone else's words against Chaitra. After all, she was so impressed by her words and her offer of a camera mobile for Shree. Shree was furious with her aunt instead of trusting her.
 
Chaitra and her lovely words influenced Shree. Shree didn't want to hear about anything against Chaitra.
 
For Shree, Chaitra seemed to be of her same age, a favourite friend who was better than her other friends. Chaitra's messages persuaded Shree to trust her. Nonetheless, she messaged Chaitra again to confirm her age, to which Chaitra responded that she was the same age as Shree.
 
Shree was relieved to receive such a response from Chaitra for two reasons. Firstly, as a thirteen-year-old kid, she refused to believe what her aunt told her. Secondly, She trusted Chaitra.
 
Shree happily texted her again, saying that best mates would be of a similar age and complimented on her earrings on how nice it looked. It might be Shree had messaged about Chaitra's earring to check Chaitra's response toward it. Shree wanted to recheck if the profile picture was that of Madhoo's or Chaitra's. Chaitra thanked her for her pleasant words. She also told Shree that she did it by herself.
 
Meaning of difficult words:
 
S.No
Words
Meaning
1.
Snap
Photograph
2.
Fascinated
Attracted or interested toward something
3.
Persuade To make someone do or believe something
4.
Furious Extremely angry
Reference:
State Council of Educational Research and Training (2019). Term-3 English Standard-8. The Mystery of the Cyber Friend(pp. 134-139). Published by the Tamil Nadu Textbook and Educational Services Corporation.