Am I obligated to financially assist my family, and am I sinful if I do not, given my difficult circumstances and their continuous demands for money?

If the questioner's father is poor and in need, then his financial support is obligatory upon her, as scholars have unanimously agreed on the obligation of supporting parents who have no income or wealth. The criterion for financial support is sufficiency and meeting basic needs. The father's financial support becomes obligatory upon his child after the child's wealth exceeds what is needed for his own support and that of his children. This applies to the questioner, as she is self-sufficient through her husband's support. As for household expenses, the husband is responsible for them, and the wife can assist him, but parents are more deserving of kindness and benevolence. It must be noted that it is unlawful for the husband to take out an interest-based loan, and there is no need to rush to repay the debt to the interest-based bank if it does not result in the waiver of interest.