There are several versions of this sad song on YouTube - sometimes the child is a boy rather than a girl, with appropriate changes in the lyrics.

"Six Weeks Every Summer (Christmas Every Other Year)"

Hopelessly the ghost of me sinks down into a chair
And underneath the cushion there's a ribbon from her hair
Just a crumpled up reminder that my daughter's only here
For six weeks ever summer and Christmas every other year.

The role of part-time mother it's the toughest role I play
Oh, my name's up there in neon lights but Lord what a price I pay
Why, the only thing it cost was giving up our used-to-be's
And my little angel baby by the name of Shelly.

Bravely I step back into my room, it's only cheap veneer
And I die inside till summertime or Christmas time is near
When up the stairs comes all my prayers yellin' mom it's me, I'm here
For six weeks every summer and Christmas every other year.

Just found a note my baby wrote she left it by the phone
She knew I'd need some extra strength to make it through the night alone
It says I'll always love you mama although I'm only here
For six weeks every summer and Christmas every other year.

Oh, I'd gladly give up all my fame if only I could hear
My Shelly calls me mommy every morning of the year...