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First of all, your source is not accurate. Rashi in fact is a proof to me. It’s the gemara that says that Acher went off because he sang Greek music (Chagigah 15b) and Rashi explains the problem by referencing that by the churban there was a g’zeirah not to sing/listen to music. Rashi conspicuously says nothing about there being an inherent problem with non-Jewish music, as you claim there is.
Secondly, I am very familiar with the situation you are describing yourself in. However it does not prove anything, and I will explain why:
When you listened to non Jewish music you were probably at a stage in your life you feel you grew past, that then you weren’t doing good things and now B”H your on the right track.
Many times we here something, see something, or even smell something and it reminds us of someone, or of another point in our life. Sometimes we don’t even know that we are reminded, it’s subconscious, but the reminder is noticeable when for no reason we start displaying emotions similar to those we would display if we were consciously reminded.
It is possible that the non Jewish music isn’t what bothers you at all. It’s the subconscious memories that come along with it. Memories you might even be completely grossed out and nauseated by.
I’m not trying to psychoanalyze you after reading one blog post. No one could do that. All I’m trying to do is show you one possibility why you might feel that way other that due to your assumption that the music is inherently evil, because I do not believe it is.
The reason I do not believe it is because I have not come across a single source in the gemara, rishonim, SA, or any literature written by someone universally regarded as a great posek that says it, and I have asked my rav and my rebbi, both of whom have shas and poskim on their fingertips, and they said the same thing.
However I do wish to note that songs which have not-nice words are definitely problematic. But that is not an issue with the music, and if you were to sing or play the song with different words and no one would be reminded of the not-nice things there wouldn’t be a problem.