Ok so I'm halfway through and first impressions are good! I have to respectfully disagree with someone else's comment who said it feels rushed. I actually think the pacing and sentence fragments are perfect for the subject matter. I think it fits your narrator's drug-fucked psychological state well, and gives the piece a sense of momentum it otherwise might not have had. Reminds me a bit of Chuck Palahniuk.
In the fourth paragraph when you start describing what all his friends are doing - I wondered, how does he know? Hasn't he been in the bathroom powdering his nose for a while now? Just a little niggle, but it jarred me out of the writing a bit. Maybe you could add 'probably'? As in, he's thinking about what all his friends are 'probably' up to outside, while he's locked in the bathroom feeling sorry for himself? Or not. It's not a glaring issue anyone else seemed to notice. I may have only picked it up because I'm reading this critically, looking for problems. :P
It’s all a formality. He doesn’t care. If he did, he would have noticed the poor job you did at wiping away the blood and the tears in your eyes.
I really like this line. Even though you told us he doesn't care, you then go ahead and show us how he knows. Plus that's a great mental image. I don't know if you did it on purpose or not, but to me it indicated how much the narrator (subconsciously?) wants someone to care, despite the blasé attitude, purposely leaving blood on his face in the hopes that someone would notice. Or maybe I'm just reading too much into it...
You never really forgave yourself for how distant you two became when you moved to Rockford. That whenever you went back to La Sardinia, you never once checked to see how he was. You never stopped hating yourself. The one person who loved you more than anyone in the world had to fight off cancer without you.
Ok so this part did feel a bit rushed. It's like you were almost at the end and realised you hadn't set up any exposition so you tried to cram it all in one paragraph. Perhaps you could drop in this info a bit sooner somehow? Also, rather than just straight up telling the reader he had cancer, perhaps you could instead describe the sickly pallor of his scalp and the tubes sticking out of his chest, or the way the grey skin clings to his skull, or how thin and frail he seems beneath the paper hospital gown, or something? It would help the reader get a clearer image of this character as well, since there's otherwise no visual description of him at the moment.
Also, 'fight off' makes it sound like he won, which, I'm assuming since you said he was dead, that he did not...?
Overall, I think your sparing use of expletives adds to the character's self-depreciation without seeming contrived or overdone. I really dig your style: the short, sharp sentence fragments and repetition. I am a little confused about the plot towards the end though, since I'm not sure (and perhaps neither are you?) where you're planning to take this. Is he hallucinating, seeing a ghost, or has somehow slipped through a crack in time back to an earlier party? Or is otherwise passed out in the bathtub and just tripping balls? It's hard to recommend possible future plot points without quite understanding what you've got here first.
Keep up the good work! :)