After Catherine dies, what is Heathcliff’s one prayer? What are his reasons for this prayer?

Here is Heathcliff's rather disturbing prayer:

And I pray one prayer - I repeat it till my tongue stiffens - Catherine Earnshaw, may you not rest as long as I am living; you said I killed you - haunt me, then! The murdered DO haunt their murderers, I believe. I know that ghosts have wandered on earth. Be with me always - take any form - drive me mad! only do not leave me in this abyss, where I cannot find you! Oh, God! it is unutterable! I can not live without my life! I can not live without my soul!'

Heathcliff's prayer sounds like some sort of gothic love poem than a prayer. He wants Catherine to haunt him. Isn't that sweet?