phrases - The usage of "got out" and the indefinite article "a" in the sentence "if it got out that they were related to a pair of"

I'm a English learner and I found the following sentence which seemed strange to me when I was reading Harry Potter and the Sorcerer's Stone (Chapter one, the American Edition): "if it got out that they were related to a pair of ——well, he didn't think he could bear it."

My first problem is that I don't know why "got out" is used here. I guess it means "it turned out that". But I looked up dictionaries and searched on website, and found no place where "got out" was used in such a way.

My second problem is that I don't know why "a pair of" is used here. I guess it refers to "Mr. and Mrs. Potter", so I think it more natural to use definite article "the' instead of "a", because it refers to a particular couple, the Potters, but not a certain couple.

Can anyone answer my doubt? Thanks in advance.

Answer

Think of it like so:

if the word got out that they were related to a pair of [what is supposed to go here is omitted because the mere thought of it is enough to gasp and immediately move on to the next thought]. [Well,] he didn't think he could bear it.

It's likely a pair of wizards, with "they" referring to the Dursleys.