Construction: Meaning of When it comes down to it

Could anyone explain what the construction means and also the entire sentence, please?

But when it comes down to it, I just can’t bring myself to leave the kids and take pictures.

Thanks

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when it comes to

Also, if or when it comes right down to. As regards, when the situation entails.

For example, When it comes to renting or buying, you’ll spend about the same amount.

It is also put as when it comes down to it or that, as in If it comes right down to it, they said you could visit any time you’re able to, or When it comes to that, we can lend you the fare.

This idiom uses come to in the sense of “amount to” or “be equivalent to.”

} dictionary.reference.com/browse/when+it+comes+to

But when it comes down to it, I just can’t bring myself to leave the kids and take pictures.

Hi Anna, what I read in your post is that you are having difficulty making a choice between being a full-time Mother and taking up a post as a photographer, and have decided,
" when it comes right down to it " that you couldn’t leave the children for the time requirements of the job.