Death Threats... I'm so scared

So Douche-bag is threatening to kill me. And he's sending the messages over the facebook, of all places.

I get the impression that this whole thing with that girl was a set-up; I was just used as a tool to play me against her ex, so her ex would feel jealous and threatened (the guy is the most insecure, tiny dicked fool I've ever seen... His picture is him shirtless trying to look tough... ooooohh you're sooo scary with your half-baked expression, and your lack of a shirt...), and so I think that the last message I sent her, during which I told her how I felt about her, and that I thought this douchebag was dragging her down, and basically told her to make up her mind; either she's interested in me, and therefore continue dating, or she's not, and that would be that. It really wasn't that much to ask IMO; either reject or accept, in the event of a rejection I would have respected her decision, and moved on.

But no. I think she either forwarded the message to the shirtless fuckwit, or he checks her accounts (voicemail and otherwise) regularly (which she had told me he had done before), who decides to start sending me messages such as the one below:

Subject: Fuck Off
Stop fucking trying to talk to my girlfriend. She's mine so fuck off. You really don't want to fucking piss me off. So back the fuck off. She's taken. So get the fucking point you ugly faggot ass piece of shit. Don't fucking call her, dont text her just leave her alone, you're doing nothing but annoying her and and me. Go fuck a cow or something around that, it might be in your league.

Oh no, so scary. The use of the word "fuck" really inculcated his points here. If he hadn't said that word so much, I probably wouldn't take him seriously. And calling me an "ugly faggot ass piece of shit" has totally decimated my self-confidence... I don't think I'll be able to go outside now. I better not piss him off, or he'll have to hurt me. Idiot. A bunch of my friends want to go kick his ass, but I've told them to stand down. If he continues with messages like these, I may give them the greenlight, but unless he really steps things up, I'm going to do things legally. And that includes shooting him if he tries to assault me at my home.

But honestly, how insecure do you have to be to send a message like that? And "go fuck a cow"? If I were Hindu or something, maybe that would have had a shred of wittiness, but honestly... Are we still in middleschool or something? I really do think that he's compensating for a certain short-coming(s)...

Oh, and if I find out that it was her that sent him my message, and she was playing me against him, I'm probably going to talk to some of the professors she's been trying to woo, and ensure they don't give her any letters of recommendation for med-schools. Having connections to some people in high places has its perks...

EDIT DUE TO NEW INFO: Well, it turns out he never saw/heard my messages. He found out I kissed her (we did more, but hey, what you don't know won't kill you), and decided to send me that message, along with others. If he had seen/heard the messages, he probably would have been at my doorstep as soon as his crappy little car could get him over here; because he sure is going nuts as it is. So this new development sorta changes my strategy. It also gets significantly changed since she told me today that she got my message and that she loved it. So now I have to decide what to do... I'm really getting annoyed, I just want to give her an ultimatum; either leave him, or don't talk to me, but I know that would just make things bad, even if she did accept in my favor. This is just way too complicated.