Jin, don't give up and ignore the stupid, coward people who sent you those pm's.
Where are you located again?
If you would like help w/training him, I can see if there is another DDB rep in your area. (sorry I can't do more) but DDB= Dogs Deserve Better and we help people who need help training their dogs,people who need help getting their dogs to the vet and help pay vet bills, etc.
Please let me know if I can help you at all. If you want to read more about DDB first before you decide here's the website
Dogs Deserve Better
Please don't give up, maybe after your dog is able to get more help and your able to get more support maybe your parents will come around and be alittle more at ease. The part that might be scary them is that he is nipping. It doesn't sound like your getting too much support from them.
I'll help you. Let me know OK.