Is the questioner considered disobedient to her father or sinful, and what should she do, in light of her father's objection to her hijab and her changed behavior towards chastity and modesty, and his accusation of her intentionally embarrassing him or refraining from helping him (by speaking with men)?

You must preserve the guidance with which Allah has blessed you: the knowledge of the truth of Islam and the commitment to hijab. You should know that your father has a great right over you, for Islam has elevated the status of parents, and nothing takes precedence over their right except the right of Allah. Allah has commanded kindness to parents and gratitude to them, even if they are polytheists or disobedient, but their obedience is not permissible in disobedience to Allah. You must honor your father and obey him in what is not a sin, and treat him with kindness and speak to him gently, while inviting him to guidance.