She treated it like a spat between a family or friends, JUST BECAUSE WE'RE both foreigners.
Or because you know each other socially. On the same (sports?) team, in fact.
Or because, without photos or other such evidence, the judge has very little way of knowing who's lying, you or him.
Judges encounter personal squabbles all the time between people of questionable credibility who pose no real threat to each other. If you believe this case is different, you need to prove that to the judge. Oral testimony is one thing, but you should gather all the physical evidence you can. He made a threat through a 3d party who offered to testify on your behalf -- great, ask him to put that statement down in writing now, before he forgets the details or changes his mind. Something like this:
1. I, ______, am a citizen of _____ and have Taiwan ARC card number _______. A copy of my ARC card is attached hereto.
2. On the ___ day of _____, 2007, at about _____ a.m, at ________[location] I was approached by _________, a _______ citizen who I am acquainted with because we have both played on the same _____ team since about ____, 200_.
3. _______ appeared to be very angry and he made the following statement about _______, a ______ citizen who I am also acquainted with because he has also played on the same ____ team since about ____, 200__: "If that fucker ever so much as looks at my wife again, I'll rip his fucking balls off and shove them down his throat" [or whatever he said; a direct quote is better than paraphrased, and it's more serious if it appears to be an imminent, plausible threat of actual violence, as opposed to a vague, general rant].
4. I have heard ______ make similar threats to others in the past, and I know he can have a very violent temper. For example, in about _____, 200__, I witnessed him [describe past violent act]. Therefore, I consider the threat that he made on ____, 200_ concerning ______ to be a very serious and credible threat.
5. I affirm that the above is true and correct and if called as a witness I would testify truthfully regarding the above facts.
Get similar affidavits from any other witnesses to serious credible threats or violent acts. Take photos of any damage he causes to any personal property. If you're real lucky and he leaves a threat on your answering machine or puts one in writing, save them.
Go to the police if you really believe there is a serious risk of him committing violence to you or your property in the immediate future, and provide them with copies of such evidence (save originals for court, if needed).
And most importantly, stay the hell away from him, don't harass him, taunt him, talk about him, mess with his stuff, or screw his wife again (