What is the meaning of “My cat was back and so was I”? Had the author gone anywhere? Why does he say that he is also back?

Explanation

After the fire the author loses interest in life. He feels that he has lost everything. After he gets books and other items from his schoolmates he feels a sense of newfound security. The recovery of his cat is like the icing on the cake. He gets back his best mate. Now both he and his cat are back to normalcy. His statement is indicating that he has begun picking up fragments of life