Try this one. The English verses rhyme and are a good translation for the Spanish, sing them after the Spanish verse. Sing the chorus in Spanish only. Sorry I don't know the middle verse. This is how it was taught to me by my guitar teacher.

Verse 1:
Es mi caballo blanco, como un amanacer
Siempre juntitos vamos, es mi amigo mas fiel

Chorus:
Mi caballo, mi caballo, galopando va
Mi caballo, mi caballo, se va y se va

He is my horse of white, bright as the dawning day
Always we are together, most loyal friends we stay

Alto a Dios le pido, y el lo sabe muy bien
Si a su lado me llamo, en my caballi ire

I pray to God Almighty, so very well he'll know
When to his side He calls me, on my white horse I'll go