Here is a poem I wrote years ago for someone who rescued and lost the cat. It is not the same situation but the theme truly does fit because you were billy's one and only friend!

My One And Only Friend

Today I came to your back door,

And laid on your doorstep.

You saw my pain and suffering,

And knew I was close to death.

You did what no other one would,

I know it was hard, but you did all that you could.

In the time I had left you held me tight,

And for the first time I felt truly loved.

Today you gave me the greatest gift

So please don't feel so sad.

You helped me to a better place,

And I wanted you to know.

How grateful I am to you,

My One And Only Friend