Is recourse to an interest-based loan forgivable for building an independent home, with the aim of escaping the harsh treatment of a mother that has caused psychological and physical ailments, while maintaining righteousness and providing for her?

Maintaining righteousness and avoiding major sins like usury is crucial, for the reasons mentioned do not justify committing this grave sin, which incurs Allah's wrath and corrupts one's relationship with Him. Patience with your mother's character and honoring her is obligatory, regardless of her actions, as honoring parents is a duty even if they are disbelievers. The proposed solution is to reconsider marriage, as it might offer a way to financially assist your mother. Legally, a husband has no right to interfere with his wife's financial affairs if she wishes to help her mother, and this can be stipulated in the marriage contract. Marriage might resolve her issues with her mother, end thoughts of usurious loans, and alleviate nervous tension.