Must a female questioner respond to her father's request for money, knowing his difficult circumstances and dire need, and that she stopped sending money due to accumulating debt?

The maintenance of a poor father is obligatory upon his well-off children, each according to their capacity. Maintenance is not obligatory upon you if you do not have what to spend on him, as Allah the Almighty says: "Allah does not burden a soul beyond what He has given it." Nor is it obligatory upon you to incur debt for that purpose. Rather, he should be pleased with some money when you are able, if he is not poor.