I am a native English speaker who has studied Spanish for a number of years, but still consider myself to be at an intermediate level and don't have much experience translating into Spanish, especially with speech that would be considered colloquial. For the most part, however, I found this song fairly easy to translate, but I feel less than confident about some of my choices. I'll list them below and if you are a native speaker or someone who knows Spanish really well, perhaps you can comment. They are as follows:

1) The verb "melt." I wondered if I should have used "derretirse" instead, but ultimately went with "fundirse" because of what I read here:

https://www.spanishdict.com/compare/derretir/fundir

(Meanings #11, #12, and #13 really kind of sealed the deal for me on this choice.)

2) The phrase "was never second best." This might be the translation I'm least confident about. I know that literally, "el segundo mejor" is a phrase that would be understood in Spanish, but I'm not quite sure if it would be used in a phrase like "was never second best" (or if it is, whether or not it carries the same meaning). In the end, I decided not to stray too far from the original lyrics, but if you have a better suggestion for this, by all means, let me know.

3) The line "the world crashing all around your face." I wondered, briefly, if I should use "colapsarse" instead. Then I looked at some collocations and was solidly convinced that "derrumbarse" was the better choice here, but if you know of something even better, let me know.

4) The phrase "stop the world." If you've studied Spanish for any length of time, you know that the word "stop" can be translated in a lot of different ways. So, I looked at a lot of different words for "stop." In the end "parar" seemed to be the best choice.

************************

BTW, this is my first attempt to translate a song into a language other than my native tongue. As fun as this was and as beneficial as it was to more fully ponder word choice, such activity is better justified if I can also get feedback from native speakers, so please don't hesitate to comment if you think you have a better translation or see something in my translation that just wouldn't be used in Spanish. Thanks in advance!