I am so dissapointed in my brother...

So my mother when to pick my brother (14M) from school today and there she met his friend's mother who pulled her aside to have a "private talk"

She told her that my brother and some of his friends have a group chat on instagram where they share... pornographic links from websites and even pictures. One of his friends in this chat got caught by his parents who told them that my brother is the one that's the most involved in this. The parents called this friend's mother and told her everything and said that they were thinking of talking to my father about this. She told them that he had passed away, so the parents didn't wanted to talk to my mother as they didnt wanted to emotionally hurt a widowed woman who already must have it hard and asked her to talk to my mother about it the next day

When they reached home, my mother immediately started telling my brother to delete instagram amd phone numbers of his friends, and I was very confused as they werent telling me anything. My mother just kept on saying, "I want him to focus on his studies that's all you know his grades are not good" I knew she was lying. She told me the truth when she sent my brother to the shop, so he thinks I dont know for now. She told my brother everything during the car ride and confessed she started crying during the talk. My mother also said that she has suspected something like from the past 15 - 20 days as he was being weak and lazier then usual (idk if this a symptom of consuming adult material tho)

I have not been able to look him in the eye ever since I got to know. I am facing second hand embarrassment and even feeling resentment against him. My mother works so hard for us, sacrifices her own comfort for us and this is what he does in return, embarrasses her through his friends and their parents.

I have not confronted about him yet as I don't want to make things awkward between us. I feel horrible for my mother, thinking how embarrassed she must have been, she was already so worried for my brother's studies as his grades are so bad, it has become worse now. She has told me to keep a watch on his laptop, but I don't know I will be able to do it as it would involve witnessing this firsthand. Also I have noticed that he would start calling me the B word in the most random moments. We would be sitting in the lounge, on our phones and I would get up to go in my room and call me that. Cursing is highly frowned upon in our house and we will get a bad scolding from our mother if we curse in front or her, and he started doing this very recently, so i wonder if this is a cause of him consuming 🌽. I always thought that he was just in his edgy teenager phase, thought it was cool and would grow out of it.

Please don't tell me "Oh watching that is normal especially for this age" it's so damaging to one's brain and literally so haram, he's sinning. I am feeling very confused right now. Should I try letting this go and simply pray that Allah SWT shows him the right path, or talk to him about it? which I really don't wanna do, as I am nervous of what will happen after