Am I obligated to offer expiation (kaffarat yameen) for swearing at myself, and am I sinful for continuing to work with my father, who consumes alcohol and curses, despite my saying to him: "May God curse us after today if I work with you or help you with anything"?

It is not permissible for a servant to supplicate against himself or curse himself. The father must be obeyed in what is lawful, for a father's righteousness is not negated by his bad manners. There is no specific expiation for this act except repentance to Allah the Almighty. Therefore, the son should advise his father, strive for his guidance, and supplicate for him.