Not the worst I've ever read. However, knife metaphors in breakup poetry is very clichéd. Also, your meter is inconsistent throughout. To understand what I mean by that, try reading the poem aloud at a steady pace (that is, not clipping endings or prounouncing two syllable words as one syllable).
... and that's all I have to say about that.
[U]ALL[/U] generalizations are [U]WRONG[/U]
[/sarcasm]