I never thought I would hatch another chick again because my very first experience was under a broody hen and it was TERRIBLE. I've hatched hundreds of chicks since then, lol. Give yourself all the time you need. Accidents happen but we learn for the difficult experience and it makes you ten...
:hugs :hugs :hugs I am so so sorry about this happening! Cats can be little terrors when it comes to peeping chicks and incubators. Hopefully, the other two will pull through for you. Half an hour without heat isn't going to kill them so as long as there wasn't too much blood loss they should...