What is Islam's ruling on the actions of a husband who abandoned his wife and son, then divorced her and married another, then returned to harass her and try to use the son to reach her, and is it permissible in Islamic law to prevent a father from seeing his son if he negatively affects the child and does not serve as a good role model?

It is not permissible to deprive the father of seeing his son or visiting him, because the father's right is great, and this right is not forfeited by him being negligent or unjust. The فقهاء (jurists) have determined that it is the father's right to see his son even if the mother has custody, and if the child falls ill, his father should not be prevented from visiting him. The father must be enabled to see his son and visit him at home in the presence of a mahram (unmarriageable kin) or outside, with an agreement on a suitable duration, and inciting the son against his father must be avoided due to its leading to the severing of kinship ties, which is forbidden in Islamic law.