When using a metallic thread it is best to use a TOP STITCH or JEANS needle. I would use at least a 16 or 18. Your thread is shredding because there is not enough room for the thread when the needle comes back up.
Also, you might want to put SEWERS AID on your thread. This is a liquid silicone that helps metallic threads slide thru the tension guides.
Never use a high tension with metallic thread. My tension may be as low as 1. Also when using metallic thread I use a thin bobbin thread.