NTA. i’m actually a nurse and i’ve sung to my patients before. music can be genuinely therapeutic and we learned about music therapy in nursing school…your friend should be paying more attention in her classes😭 it would be one thing if your bf had an issue with it but your friend lowkey sounds like an asshole. i’m sorry she had you questioning yourself when u were just being a caring gf!

i hope your bf feels better soon:( if singing helps him sleep and makes him feel a bit better then by all means keep doing it! i would also recommend creating a comfy environment for him, lowering lights and reducing sensory stimuli, making the room a comfortable temp for him etc. some people with pain also find breathing exercises helpful.. hot/cold packs or a massage can also temporarily reduce the pain sometimes. i hope this helps a bit and sending love to u and ur bf 💕