I did some looking, and it's so rare that there aren't any go-to statistics to cite. There are some reports of men committing murder after a paternity test, but it's unclear to me how what you're saying is anything more the speculation.

It might actually be that mandatory paternity tests reduces the background rate of familicide. All of the reports that I could find were only after the father had invested considerable time into raising the child as their own. The stakes of the deception are much higher. But if they know the day the baby is born (or earlier), then it's much easier to walk away. It also makes it pointless for the deception to happen in the first place.