Help me save Jasper's leg

The night before Mother's Day, Jasper decided to get the zoomies, knock something over, wake the dogs up (and me), and try to play at 2:30 in the morning. It was dark and I went to go see what happened, when Jasper ran under my feet. I tripped and stepped on him and broke his leg. The Emergency Vet initially told me that Jasper needs surgey to place metal pins in his leg because the break was so severe. And If I wasn't able to spend the $5,000 on that surgery, then I would likely have to amputate his leg (estimated $3,800) and it is very unlikey that it would heal on its own. So, 7 hours and $1,000 later we left the Emergency Vet with a cast, some pain medicine, and hoping for a miracle.

Understandably, Jasper hated the cast and proceeded to slither and squirm his way out of 5 casts... On top of the normally scheduled biweekly rechecks we had. ($650 in Vet Bills from those visits)

It has been 8 weeks as of now and it's still not healed. Today the Vet took the cast off completely because it wasn’t healing. They hope it will “jump start” the healing process if we let “nature” try. We scheduled an appointment for them to check it again in a month but since they removed the cast earlier today, he’s been chewing at his leg and making it bleed. His leg literally looks worse than it did the night it broke.

I dont think we're going to make it the month for the next checkup. Especially if he keeps gnawing at his broken leg. And then the only option we have is surgery.

So please, help me save my cat's leg.