Doom and gloom!

This is (or was) a nest box located on a scots pine tree at the end of our garden. It has been there for five years, one of several around our garden - put up for the tits to nest in. Early this morning I disturbed the large ginger cat which regards our garden as his private toilet ( my vegetable bed, thank you very much!!) from the base of the tree. He leapt up and over a six-foot fence to escape me.
Then I noticed the nest box broken from its moorings and hanging upside-down.
This has been the first year the box was occupied - in this case by a pair of Great Tits, which had been busily feeding their young ones up until yesterday.
I will examine the box shortly when I have taken it down, but I know in my heart that this will be bad news. I am heartbroken, as if cherished members of my family had been spirited away. So sad, and very angry with one large ginger Tomcat!