Enloquecer means "to drive crazy" or "to go crazy." It's a dramatic and intense verb that conveys a strong emotional state.
In the context of this song, the singer uses it to express the depth of his passion, stating, "la besé hasta enloquecer" (I kissed her until I went crazy). This highlights the overwhelming and consuming nature of his desire and affection, making it a captivating word choice.
"Todo Lo Fue" ("Everything It Was") is Lenin Ramirez singing about a love that had to stay hidden. He remembers exactly what it felt like to know her, want her, and never be able to have her out in the open.
The chorus lingers on that memory: how well he knew her, how badly he wanted to see her again, and how much it would have meant to call her his own, even though the relationship was secret and forbidden and turned his whole world upside down.
By the second verse he is left with nothing but the memory. At night he replays what they had and imagines what they could have become, and then the chorus comes back around, because the wanting never really goes away.