Ivan Seeking said:
I think it sounds pretty good [very good actually] but I can definitely detect a slight accent.
That's because it's not an Oregon accent.

Danger may have called it though...maybe it's a bit of a Puerto Rican accent...but, it's tough to really say what's an "American" accent anyway. If you're in NYC or northern NJ, you'll hear a different accent every few blocks.
Though, we should ask...is it supposed to be a "generic" American accent, or does the story define what part of the US the character is from? For example, that's definitely NOT an accent typical of the southern US, or the midwest. I would definitely place it as an East Coast city. Maybe Miami, maybe NYC.
When you say money, it sounds to me more like monney. Try saying it like "munney"
I listened to it three more times, specifically listening for that word. I don't hear anything wrong with it at all. It does sound like "munny" to me.
Finally, be careful not to sound melodic. To when you say "to much", there is a slight rhythm in addition to improper inflection, and as stated, a short decay on the word "to".
I wasn't sure if he wanted us to just comment on the lines and accent, or if he wanted us to address the "acting" style as well. I figured he needs to get the lines down first. Right now, it doesn't sound like someone who's really angry, it does sound a bit like a dramatic monologue. But, I figured he needs to learn the right lines before he would work on getting the emotion to come across right.
But, if that's part of it too, then for example, "I KNOW you're ----ing my girlfriend." Currently, "know" sort of rises and falls in inflection, and it needs to be "punched" more.
Same with, "You really do deserve to die." I'm not sure where the emphasis belongs in that phrase, because I don't know the context. Is your character standing there about to execute someone for stealing his girlfriend, in which case the emphasis should be on deserve, and maybe drop the "do." "You really DESERVE to die," sort of justifying what he's about to do to him. On the other hand, if this is a warning to stay away from his girlfriend, and he's saying he ought to kill him for what he did, but is going to let him go this time, then emphasis should be on "die." "You really deserve to DIE." If the latter is the context, I'd suggest changing that line to something that's more of a direct threat. "Y'know, I oughta shoot you. You've been a lousy friend, going behind my back, stealing my money, and, now you're -----ing my girlfriend. Look, man, I know you're stealing to cover your debts; you gamble too much, you drink too much, AND you love the ladies too much...but, you* stay the hell away from mine!"
*pronounce "but, you" more like "bu-chya"
For the former scenario, one where you're about to kill the guy you caught sleeping with your girlfriend, maybe change up a few other lines,
"Man, you DESERVE to die. You've been a lousy friend, going behind my back, stealing my money, and, now you're -----ing my girlfriend. Look, man, I know you were stealing to cover your debts; you gamble too much, you drink too much, AND you love the ladies too much...buT, you should have stayed the hell away from mine!"
In this case, pronounce the T in "but" and pause for emphasis before "you." In the former example, it's all a threat with the anger seething below the surface still under control...barely, to be done in a low voice, maybe a lot of clenched teeth, but in the latter, it's not a threat, you're going to act on it, and you're telling the guy why you're about to put a bullet through his head.
Your lines were good too. It just gives a different tone, so I'm offering these as alternatives depending on how the scene fits into the larger story line. Your version sounds more dramatized, like the sort of monologue a character in a daytime soap opera would speak, or what someone would say whose been thinking over it for a while and is more of a professional killer who is not acting out of anger/passion but has been plotting it for a while and the person he's about to kill is just another hit of many he's done before.