(Note - I review pretty harshly, so don't take a low score personally! I don't vote harshly.)
I don't listen to a LOT of hip hop, but I think I listen to enough to be able to judge. (I really like A Tribe Called Quest if that gives me any credence ;P) Your flow is pretty decent actually, it'll need a little bit of work, but it's pretty good. I think you should give the beat a bigger presence though, since the beat is a really crucial aspect of hiphop.
And finally I have a bone to pick with your lyrics, which need some work. I'd suggest a little more care with your rhymes - girlfriend/end or hope/throat is kinda silly :P. Word choice could improve -"your life will quickly end" is a little clunky. I also think the topic could be improved.
I just saw on audio advertisements that this was your first rap track. It's a pretty great first try! Your flow is actually really good for a first time through. Keep it up!