Like I said. Don't feel bad for letting her go. I really do get it.
I just forgot the woman's name, and I don't know how to quote from other threads. A moderator said you can tell it is Gape worm by taking a Q-tip and GENTLY swirling it in the throat, and down about an inch or so, then swirling it on the way back up. They should be on the swab, and she thinks they are red.
As far as seeing something, I have not heard of anyone saying they could see the worms. Treatment is a matter of finding the right kind of wormer. I really can't remember what kind to use. Someone should be able to tell you in the morning (I assume most people are out for the evening or in bed).
I hope your others are okay. Do what is best for YOU! If that means starting your flock over, that is what you should do.

Sleep well tonight, and don't worry about it. The answers will come tomorrow.