Who Betrayed Bess?

And dark in the dark old inn-yard a stable-wicket creaked Where Tim the ostler listened; his face was white and peaked; His eyes were hollows of madness, his hair like mouldy hay, But he loved the landlord's daughter, The landlord's red-lipped daughter, Dumb as a dog he listened, and he heard the robber say—
V
"One kiss, my bonny sweetheart, I'm after a prize to-night, But I shall be back with the yellow gold before the morning light; Yet, if they press me sharply, and harry me through the day, Then look for me by moonlight, Watch for me by moonlight, I'll come to thee by moonlight, though hell should bar the way."

I have copied and pasted this part off the poem. I got this from Alfred Noyes, The Highwayman.
I think in this part of the poem it tells us that perhaps Tim the ostler boy is the one who betrays Bess.