As a general piece of useless trivia: Black Widows (or many intraspecies cannibalistic spiders) don't actually eat the husband out of any specific need or reason, they just don't rate them jack shit past doing the dirty and outside of that specific window, they get eaten like any other prey animal. So the cannibalism isn't a switch being flipped on, but instead the big horny switch being flipped off and its other needs coming back online.
So, as long as she hasn't snacked on him yet, he should be golden. On the other hand, there is differing levels of Matriphagy in many spiders, so the momma might need to be careful of her brats and/or impulses after any family additions.
