Welcome to the wonderful (and expensive) world of rug wrecking! Firstly, does the rug still function as a rug, despite the rip? If so, perhaps you can leave it. If not, I'd stitch/patch the flap of ripped rug to the strongest available bit of remaining rug (usually a bit of binding somewhere). Leatherwork needles are good to use because they can get through the toughest binding. I you want to waterproof the repair you can use a tent repair kit. If you need a replacement clip, you can often buy one from a cobbler or nick something off an old leadrope. If you ever have a rug that's ripped beyond repair, keep it as patch material & for spare clips, buckles etc. My old horse used to destroy rugs on a regular basis, but only certain ones that I think he found uncomfortable. There were certain makes that he would always trash. Eventually I figured out the sort of rug shape & weight he liked and things improved. Perhaps each dead rug should be treated as a learning experience?!