This is quite dark. I like how the tone turns bitter in the last paragraph.. leaving the reader with a sick feeling of realization of what he/she read. I will admit, this threw me off-kilter a bit when I figured out what ‘it’ was.

I had to look at the tags to make sure I reached the right conclusion.
I agree with Madi, quite dark. And a pretty perfect description of how this kind of thing happens.

this is just a fantastic ficlet. this is what i save 5 pencils for.

Ouch. I hope this is in no way autobiographical! Tremendous atmosphere here. IMHO the fist section might be a little better like this:
The recipe is simple: a sour friendship and a torn heart.