(((((hugs))))) If she just went along she wouldn't be a difficult child, would she? It is awesome that you left the room - this is something you already know you cannot fix. It is time to let them do their job, not time to do it for them and make her eat yourself. This is the ONLY way they will see what you deal with daily, hourly, minutely.
I am sorry it is so rough on both of you. her fears of dying if she tries to eat are not something she is making up or pretending. It has to be hard to see, and hard to understand, but they are going to HAVE to deal with this like a real PHOBIA not just defiant behavior. Do some research on exposure therapy and suggest they look into trying that with her, rather than just telling her to try to eat. It might do a whole lot more than what they are doing?
Many many hugs to you. I am SO sorry that you and difficult child have to deal with this.