What should I do about my inability to marry and Satan's incitement to fornication, given my responsibility for my siblings, my grandmother, and my poor sister?

The religiously prescribed remedy for someone unable to marry is fasting. The Prophet, peace and blessings be upon him, said: "And whoever cannot afford it, let him fast, for it will be a shield for him." Fasting diminishes desire. If a person fears falling into adultery, and fasting does not curb their desire, then marriage becomes obligatory, irrespective of expenses, because protecting oneself from adultery is among the most emphasized obligations. However, it is mandatory to inform the woman about one's financial hardship.