Irrational fears!

My neighbour, who lives just across the street, was robbed 5 minutes ago. The burglars got in by a small kitchen-window she'd left open. She was in the house, her car was parked outside, but they didn't care! They got in, took some things quickly and ran away.

My neighbourhood is a very peaceful place where we can leave windows open like she did. What happened today isn't expected to happen again soon. But I'm now getting obsessed over this, and I'm going to start checking around my yard and waking up at night to check again because of a stupid noise, etc. 

Does anyone else get obsessed like this over irrational fears?

What do you do to get over it?