The belt wouldn't have broke because it was a few years old, there's a reason it broke. Depending on how bad your idle is jumping or could have been your learning to drive a clutch, bottom line is, from the looks of the belt in the pic, it lost a couple ribs along the side. This indicates the belt jumped a groove or two which ultimately led to the belt breaking.
Start with getting the belt replaced and that idle issue resolved. Then watch for the belt or idler pulley jumping around or the belt trying to walk to the front or rear, could be a pulley mis-alignment. Can't really do anything until you get the belt replaced...do yourself a favor and order 2.
According to this
https://www.hksusa.com/application/f...-A40011-00.pdf
"the V-ribbed Belt cannot be installed after the Supercharger is installed to the engine." Dumb design, but...OK.
If you're not up for the task of replacing the belt, solicit the help of a friend that has some mechanical chops to assist or you'll need to have it towed to a shop.
FYI. There's some information about belts sizes in this thread
https://www.ft86club.com/forums/show...=89226&page=35