Did the questioner wrong his son or himself by placing him in an unsuitable environment, and can he marry again after two failed experiences?

The fundamental principle is that custody belongs to the mother upon the separation of the spouses, unless there is a preventing factor such as immorality. If the woman's immorality is proven, she has no right to custody. Custody matters are referred to the Sharia judge for adjudication. If you are unable to remove your child's custody from his mother, there is no blame upon you. The establishment of custody for the mother does not prevent the father from seeing his child, caring for him, and disciplining him. Furthermore, your previous marriage does not prevent you from marrying again, with an emphasis on choosing a woman of religious commitment and good character, and paying attention to appearance and cleanliness, especially oral and dental hygiene.