As-salamu alaykum,
I am sorry to hear your so is treating your husband this way. While you did not mention your son’s age, perhaps he needs to go on a family excursion to visit the poorest of the poor and do some charity work. I would kindly suggest getting him involved in charity work with the homeless or immigrants/refugee’s who are in desperate need. I would make this part of his weekly routine. Insha’Allah seeing those less fortunate than him will soften his heart and give him a new view and appreciation. I would kindly suggest getting in touch with some local Islamic organizations who are doing charity work and get your son involved.
While you and your husband have provided your son with an adequate life and sacrificed much alhumdulilah, he is spoiled and ungrateful. Please never doubt your or your husband’s efforts dear sister, you sound like wonderful parents!

Lastly dear sister, his disrespect and cursing of his father is haram and should not be permitted. Should he continue, consequences should follow such as taking things away from him, grounding him as well as reminding him of Allah’s wrath should he continue this most despicable behavior. Please do draw close to Allah, be supportive of your husband as I am sure it hurts him as well. Also make duaa to Allah SWT for ease in this matter. You and your family are in our prayers.