What should a young man do who has come to despise his parents due to their ill-treatment of him?

Islam urges the maintaining of kinship ties, and Allah has associated the cutting of these ties with corruption on Earth. If the ill-treatment from relatives is due to a religious matter, then be patient, seek reward from Allah, and have compassion for them. If it is due to a worldly matter, then respond with that which is better, and meet evil with good and patience. Be as the Prophet, peace and blessings be upon him, said to someone whose relatives maintained ties with him but he cut them off: "If you are as you say, then you are feeding them hot ashes, and you will continue to have a supporter from Allah against them as long as you persist in that."