Nothing helps someone to talk some sense into someone else like a loaded gun. They came back to hide their vehicle? They knew him, he knew them. He knew where they lived. How was hiding their vehicle going to accomplish anything?Because she knew he could be violent but she may have thought she could talk some sense into him.
Now that there are two scenes where bullet casings were found it shows why they came back and tried to hide their vehicle so he wouldn't see it.
I think he went ballistic with rage.