"The Apparition"

"Bathed in a cold quicksilver sweat, wilt lie

A verier ghost than I" (12-3).

In "The Apparition" by John Donne, I kept thinking about how this completely negates everything I learned from Casper: The Friendly Ghost.  I felt like the tone was definitely revengeful.  Donne creates this tone by his very scary imagery of wanting to get back at an old "murderess" lover.  The diction in this poem confuses me.  Literally, it sounds like the speaker is truly a ghost, but I think that it was more metaphoric for killing the speakers sanity.  This really only makes sense logistically and does not have much text support (other than maybe line 8 and 13).  If the speaker wants revenge, then simply being a ghost would leave them incapable of any physical ability for revenge.  I think that the idea of a ghost is a metaphor for the speaker being invisible to the former lover.  In line 13, the speaker wants to make his old lover a "verier ghost."  I took this to mean that the speaker is not a ghost, but that he wants to make the cause of his broken heart a true ghost (e.g. dead).