A. Whether the person is a Hafiz or not, it is the obligation of a Muslim to hide the faults of another Muslim. The Hadeeth promises great benefits for hiding the faults of another. In this case it is your own brother who has more rights over you than any other person.
If you can speak to him and advise him then do so with kindness and dignity, without belittling him.
If you cannot speak to him, get someone else who is trustable and pious and to whom your brother will listen to and respect. This person must be such that he will not divulge any information to others.
Make Du'aa regularly that Allah Ta'aala guides him.
Mufti Siraj Saheb adds:
It is imperative that you make all out attempts to help your brother. You might want to tell him that this information will be divulged to your parents, and if need be, inform your parents so that they may address the problem. The matter is serious and your brother needs urgent help.
May Allah Ta'aala guide him and all of us to His pleasure, Aameen.
Moulana Yusuf Laher
Checked by: Mufti Siraj Desai