Should the questioner submit to her husband's desire and pressure her father to mortgage the house in order to give her husband money, or what is the most suitable solution, especially since the husband is threatening her with divorce and harming her parents and son due to her refusal?

The wife should not give her ill-spending husband any of her money or her father's money. Instead, she should advise him to fear Allah Almighty and seek lawful earnings. The wife has her independent financial responsibility, and she is not obligated to give her husband anything from her money. The husband, in turn, must treat his wife with kindness, not mistreat her, and he must be just and benevolent. He must also fear Allah concerning women. If the husband does not cease his threats, the wife should not make him covet her money.