He pretends to be a girl so that he can get the names of bad websites and get them closed down

Our advice to you is not to do this thing, because by doing it you are exposing yourself to danger. Even though you have repented, and we praise Allah for this blessing, the Shaytaan still flows through the son of Adam like his blood. No one should expose himself to temptation. We advise you to make use of your time in doing good things that are of great benefit, such as reading and memorizing Qur’aan, keeping company with righteous people, and seeking knowledge of sharee’ah and the Qur’aan and Sunnah from scholars who practise what they preach. It is good to visit beneficial Islamic sites on the web that spread good according to the way of Ahl al-Sunnah wa’l-Jamaa’ah, following the righteous salaf, may Allah have mercy on them. 

We ask Allah to reward you with good for your zeal, and to make us and you steadfast in adhering to the truth until we meet Him… Aameen.