All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Homosexuality is a dangerous disease and a grave major sin, so if it is proven that that man is homosexual, then it becomes incumbent upon you to advise him and remind him of Allaah. For more benefit in this regard, please refer to Fataawa 90562 and 88137.
If advice is of no avail to him, then you should desert him if it is hoped that this is beneficial for him. Also, if you fear that your son may be harmed by him, then you should find a way so that he does not stay in seclusion with him in order not to corrupt him, as you are responsible for him in front of Allaah.
Ibn ‘Umar narrated that the Prophet said: “… a man is a guardian of his family (household) and is responsible for the people under his guardianship,…” [Al-Bukhari and Muslim] Hence, you are not permitted to be lenient or negligent about your responsibility.
Moreover, if the matter requires that you prevent your wife from work, then you should do so; because her taking care of her child and protecting him from harm comes in priority over her work.
Dear brother, you should know that protecting your child from harm does not contradict your wife keeping her relationship with her brother. Indeed, you are the protector, the provider and the leader of the house, so take a decisive action and do not be negligent.
Allaah Knows best.