I like what the IDOM and others had to say, though I think I liked the music more than he did.
I was thinking that the jump scare at c.2:24 was really well executed and I wanted to compliment you on that one.
The scene in which the ghost or zombie of the girlfriend is standing there in the car park and then especially the close-up of her face at c.3:33 is a little wanting. It's tough when you don't have a budget for wardrobe and some serious makeup. But if I had that to shoot to over, I think I would have try to do something a little more with, perhaps, her outfit when she's standing there back-lit. And I would definitely want a more sinister, spooky, and/or, more to the point...a more convincing makeup job for the closeup of her face. If that wasn't possible, I think I just wouldn't show her face so closely. If you can't afford an excellent effect, or if it just doesn't work well, it's best to not show it directly, explicitly, I'm thinking. Perhaps a cheap alternative to showing the closeup of the inadequate makeup would have been a medium or medium close up shot from
behind her semi-silhouetted back and head.
Or, maybe put more into the makeup.
Looking at it even more closely in pause, I think the acting might also be at issue. What if, somewhat in foreshadow of what is to come, the actor had had the same expression as her "corpse" did when lying on the bed just after the overdose? Now that dead look might have been chilling and made the makeup less important to me.
The series of shots revealing the twist: the relationship with the girlfriend, the drug use, and related death is done so well. The build up to that is also done well. But I'm left feeling that maybe the build up might benefit from being shortened and tightened a little bit.
I also think I agree with IDOM about that ending bit. While I do like that closeup shot of the drug paraphernalia aesthetically (It is nice to look at, well done.), story first, so I think IDOM is right about it being overwrought --storywise.
Very nice work. Looking forward to your nest film.