All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
First of all, if the conduct of your wife's brother is as you mentioned, then he has combined unemployment with committing sins. We advise you to be patient with him as long as there is hope in his reform and to avoid discord with your in-laws because of him. The outcome of patience is always good; please refer to fatwa 83577 about the virtues of patience.
Secondly, you should supplicate Allah in his favor and implore Him to rectify his affairs. Indeed, supplication is an essential and important means to accomplish one's objectives. Allah, The Exalted, says (what means): {And your Lord says, "Call upon Me; I will respond to you." Indeed, those who disdain My worship will enter Hellfire (rendered) contemptible.} [Quran 40:60]
Indeed, Allah, The Exalted, is able to rectify his affairs in the blink of an eye, so place your trust in Him.
Thirdly, you should continue to advise him and seek the help of wise people whom he would listen to to clarify the importance of striving to earn a living and the reported forbiddance of staying idle without work to him. He should be reminded of the like of the hadeeth narrated by Hakeem ibn Hizaam, may Allah be pleased with him, in which the Prophet, sallallahu ‘alayhi wa sallam, said, "The upper hand (which gives) is better than the lower one (which receives); and begin (charity) with those who are under your care; and the best charity is that which is given out of surplus; and the one who seeks chastity, Allah will grant him chastity; and the one who abstains from asking others, Allah will make him self-sufficient." [Al-Bukhaari and Muslim]
He should be told that his idleness may be the reason for engaging in sinful talks with women, and it may lead to more serious sins in the future. He should be advised to repent to Allah of such acts. If he does not stop, he may be deserted if it is hoped that deserting him would help deter him.
Fourthly, you should consult with his wise relatives and discuss his situation, clarifying to them that you do not approve of his actions and that you may ask him to leave your house. This would reduce the negative effects that may result from kicking him out of your house that should be the last resort after all other possible means have been exhausted, just as cauterization is the last resort in treatment.
Allah knows best.