Was my staying by my father's side while he was playing music, out of fear of his anger, right or wrong? And is it better to leave the gathering immediately upon hearing music, or to wait a little to avoid being accused of disobedience or of offending one's parents?

You must honor your father and be good to him, and advise him with wisdom and gentleness to abandon forbidden things like music, even indirectly. However, it is not permissible to sit where evil is present. If your father listens to music, politely excuse yourself, citing the prohibition of music or your engagement in another matter. If you forbid the evil and he does not respond, and you are unable to leave his presence, then there is no sin upon you for merely hearing the sound of music, as long as you do not intentionally listen to it.