Should I go with my dog to be euthanized?

My dog has rapid spreading cancer and We need to put her down before she suffocates from the cancer in her throat. I live with my parents and this dog was my childhood dog. I don't know if i can psychically sit in the room and watch her take her last breath, my parents will be in the room with her and i also don't know if i can watch my parents be so sad. But i am scared of the regret i might be filled with for not going. Please help because i dont want to regret this.

This is an update because a lot of people are reading this wrong. I am still a minor and don't feel comfortable sharing my age. She will NOT be alone because my parents will be there. But ultimately I have decided to stay with her. I am not neglecting her I have an insanely hard time around death and don't know if i can fully handle her taking her last breath. I needed to update so I would stop getting so much hate over something that the hardest decision I have made. Thank you to certain people for all the kind words.