ANSWER:
You must not despair of Allah’s mercy. Listening to music is not permissible in Islam. You feel bad about it because you know that it is haram so you must repent to Allah while showing deep remorse and sincerity and not do this again. The biggest problem and fear is that after a while, your heart would be accustomed to such a sin, you won’t even feel remorse or sad for doing it. This is when your heart would have begun to die bit by bit.