I let my baby cio and now I feel terrible 😔

So I have been working on sleep training my 7 month old. I have been using the Ferber method of cio with checking in at regular intervals. It has been working well, he has never cried for more than 5-10 min. Last night however it lasted 1 hr and 15 min. It was so awful, but i didn’t want to give in and nurse him bc it had only been 2 hours since the last feeding and I also read that if you give in it makes the time you just allowed them to cry a waste...

But he has been sooo fussy all day today and I’m worried it’s bc I let him cry for so long and it’s affected his trust in me and the world. I just feel terrible and I’m really dreading tonight. I don’t know what to do if he starts crying.

I don’t want to go back to nursing every time he wakes up bc it was turning me into a zombie. Ugh I feel like the worst mother ever 😓