I'd say you got very lucky that nothing else broke. I've seen some of those adjustable links bent a little bit but never completely pretzeled like that one. As many others said, the 3pt is not made for pushing backward. I still push backward a little bit with the box blade and grader blade, but I use common sense. I learned the hard way shortly after we bought the tractor almost 3 years ago that pushing backward and digging backward with the box blade is a no no. Bent both the bottom pins and tweaked the whole hitch assembly on the box blade. Replaced the bottom pins and it's been fine, Actually works with the new quick hitch with the KBOH extended top hook. I still run backward with the box blade and blade, but I try to only move small amounts of material, and only move loose material, not digging into virgin soil.
The simple answer is don't push backward at all with it, the longer answer is if you are an experienced operator and have a feel for the machine you technically can push backward with you implement and not damage anything, you just have to be very very careful and know your limits.
The simple answer is don't push backward at all with it, the longer answer is if you are an experienced operator and have a feel for the machine you technically can push backward with you implement and not damage anything, you just have to be very very careful and know your limits.