The music major at Columbia is an academic major, not a performance major. It includes theory, ear training, music history and other topics, and to some extent, there is credit for lessons and performance. I assume any opera performance would be extracurricular.
https://music.columbia.edu/undergraduate-study/music-at-columbia-college
You can do lessons and performance there without majoring in music, right?
Carnegie Mellon, on the other hand, offers a BFA and has an actual vocal performance program in the degree. And, of course, a BS in computer science. https://www.cmu.edu/cfa/music/programs/undergraduate-programs/index.html
If you go to Columbia, I would think you could start out in computer science, which is a pretty intense and sequential area of study, and participate in music in extracurriculars, and take some electives.
Have you committed to a double degree at Columbia in some way? I am confused about your status.
I really hope you can relax a little about career outcome. Clearly computer science affords a relatively reliable way to support yourself. Music majors do all kinds of things, and yes some continue in music, some don’t.
Is the “3” in the 3-2 computer science? This sounds like a stressful way to go. I would think about doing CS with music on the side unless you truly want to do vocal performance, and if you do, Columbia doesn’t really offer it formally.
Am I missing something?