B/c you care/cared for him that is why its hurting so much...
you say you hate hime but then only reason you feel that way is b/c you care.. its a concern.
so sorry but your better off .. just remember that

that is so wrong what he did recycling the ring WTF is that!! he couldve resold or something that ring and got a different one ..
his new fiance is crazy... i would never accept a used ring....