Two days ago I was checking the eggs and taking off bits of shell from the nest (one egg must have broken, no chick inside), and while I was candling one it fell on the floor, breaking beyond repair.
There was a baby inside, I can't even describe how I felt

He was not completely formed, more of a little blob, but still, I feel so bad about it, I was sure they were all not viable due to all the moving of the nest and the fact that the parents left the nest for a few days.

And that's why I try NEVER to touch the eggs! I am a baby killer. Seriously it was horrible.

I'm sorry you lost the egg, but accidents happen sometimes and that's just the nature of life. It's sad when a viable egg is lost, but there will be other eggs in the future if you want them.

I'm sorry you had such a sad experience. I would feel the same way. We have to remember that even in the wild some eggs get damaged and don't survive.

I'm sorry. I've done that before. I saved a blackbird egg from a bluejay and then I dropped it and it broke.

That was a big disappointment, but accidents happen.

I am so sorry. Things often happen that we wish we could change but accidents are nothing more than accidents. Take care.

Sorry your feeling bad....
Yes accidents happen... the way of life....
Your a good kind person to all your flock, so don't feel too upset...,

Thank you all for the kind replies.
I haven't had time to post about this year's Trilly & Frank's egg adventure, I will do it soon.

They have a multitude of eggs in the nest but I am not sure any of them will actually hatch. I would love to have some little ones here flying around in time for Xmas, will have to wait and see... The nest has been up for a while now, they are very diligent as usual, but nothing happened yet. Fingers crossed!

I hope things work out for your eggs. Sorry about the broken one, I would feel awful too
I just recalled, when we had the first egg of the second clutch, I decided to clean the nestbox from the poop of the first clutch, and I used a napkin to pick up the egg, then I put it on the sofa wrapped in napkin (what a wonderful choice of location, huh?). Then we put a piece of the cage (I was cleaning the cage) right where the egg was. There were no visible damage to the egg, but it didn't hatch on time so who knows..... I also try to never touch their eggs.
My cockatiel is named Trillie (pronunciation is the same I guess) , but he is a boy. Is it usually a name for a girl?

Well, I think it's a made-up name so we can spell it as we like
I know a dog called Trilli and she's a girl, but I think it's a pretty name for both sexes!

A trill is a musical effect with no gender whatsoever, and with cockatiels the boys sing more than the girls do. There was a female character called Trillian in The Hitchhiker's Guide to the Galaxy. But once again it's a made-up name, so it can be applied to anything you like.