Until hearing is lost one doesn't appreciate how much the bones in the head tell us about sound.
Pre-op (when the hearing in my AN ear had dropped to 30%) I could sing just fine and had no hint of loss of pitch. I found that I developed an increasing irritation with bad singing. Our church choir singers are mostly untrained volunteers, so I run across a wild one once in a while. I have natural ability to copy, sustain, and find a pitch. I harmonize by ear. For twelve years I have been the person in the choir who calls the office to get the piano tuned again. I have retained all of that ability in spite of my 2005 Translab and SSD.
Post-op I have less tolerance for off-key or bad pitches. Post-op I have better luck singing alone, with a well tuned soprano, or accompanied by a well tuned instrument backup. I still harmonize well and hear myself in my head and with my good ear. I have natural pitch and I read music a bit. Others tell me my singing is the same. Since I started using a bone conduction aid I am better able to hear myself singing, and I am better able to hear nuances of the string chords. I doubt I'd be able to sing with a loud group or near brass instruments. My tinnitus would be too outrageous.
So, I encourage you to keep on singing, learn to ignore tinnitus. Continue to enjoy your vocal gift.
I can't say I regret surgery. My tumor was ready to come out. I was not prepared to have it swell and wait for it to die, not at my age. I am 65. I want to be positive with you. If my young family member had a small tumor I would investigate treatment that might promise preservation of the some hearing. Of course, even my family members have the right to make their own informed decisions. There is a lot to consider I know.