Hi Adrian
I am really sorry for what happened to you.What should have been fun turned out in a cruel spanking from people calling themselves experts and,maybe, teachers.
Please consider yourself as a pioneer,with the courage to experiment with software like Vocaloid in an otherwise nice song.
As an every day musician ,I liked what I heared in You Tube.
I am sure that there are lots of true musicians in this Forum who are willing to guide you further in your efforts in a decent and friendly way.
Don´t be too disappointed and keep on the good work.
Regards