My(21) mom(45) and I both sing in a choir together. Recently our choir director, Natasha(58), promoted the youngest member of the group, Tim(17), to assistant director, now this upset a lot of the choir as most members are 40+ in age. Last week Tim came to my mom and I asking if we'd be willing to sing solos in a song he wrote, of course we both excitedly agreed as neither of us had an issue with Tim becoming a director. Today's rehersal was Tim's first day directing on his own without Natasha, and also the first day of the choir working on the song he wrote. We went over the chorus and backing vocals where everyone sings and things were running smoothly up until we got to the solo verses. I sang my verse no issues for the most part(I was late on my entrance but besides that it was good), then we got to my mom, she sang fine except for the fact that on the last word of every line she was flat. Tim stopped her every time she was off and told her to go down just a little bit(she never even got to the second line of the verse) he even gave her an alternative version where she wouldn't have to go up to the higher note he initially had written. Everyone told her if she wasn't comfortable not to force it, trying to be supportive and stuff because my mom used to be very shy regarding music solos up until a year or so ago, she still gets a bit nervous holding the microphone. Anyways my mom has to leave rehersal early for a doctors appointment so Tim gives my mom's part to me and the rest of rehersal goes fine. Later on when I get hom my mom is ranting about how rehersal went saying "I was doing exactly what you were doing but whenever I do it I'm wrong". So I bit the bullet and told her she was pitchy and she retorted with "How am I supposed to sing it right if he's giving me 5 different notes"(mind you he gave her 2 different versions he said she could choose from not 5), "If I was off pitch why didn't he just say that", "I know I can sing I got accepted in a different choir thats invite only", and "Whatever it's not my solo anymore"(I fully intend on giving her the part back if she ends up learning the right notes). Anyways I don't know I feel bad about it, but was there a better way I could've gone about giving her feedback?