I liked this story for a look into domestic violence.  There were a couple of things that distracted me out of the scene though.

First, there were many point of view (pov) shifts.  You shifted from the Katie's pov to the children's to Johnny's and then the cop's.  I think the story's tension and message would be better presented in the mother's pov only.  

The reason I say this is that you could make her fear real for the readers.  She's crouched in the corner of a closet.  Show us the door rattling on its hinges everytime the husband bangs on it.  Let us hear the children sobbing and see their noses running with snot, if they're really young.  Does she freak out when she think the phone line goes dead while she's talking to the 911 operator?  Make it intense.

One other thing that distracted me was "delicate bruise".  It seems the wrong adjective in this scene.  It a brutal scene, not delicate in anyway.  

I liked the way you preceded the mother's death with the death of the female cop.  

All in all, I liked this story.  Thank you for posting it.

A note about POV:  In storytelling, POV can be a tricky matter.  It’s generally advisable to stay with one character, especially in a short story.  In novels, it’s considered OK to switch , as long as there is no more than one POV per chapter.

Sometimes, though, even in a short story, it’s necessary to switch POVs  to tell the story properly (so long as it doesn’t  distract the reader).

When reading Love Shouldn’t hurt,   I noticed the POV switch, but didn’t find it too distracting.  Like Priscilla, I enjoyed the story and found it to be a look into domestic violence.