Bit by severed rattlesnake head

My husband & I were doing regular yard work in the back yard, when I inadvertently reached for a rattlesnake that I didn’t know was there when I reached down to pull out some grass/weeds growing by my flowers in my garden seating area. This did not make the snake happy at all. My husband killed it to defend me. About 10 mins later he went to dispose of the snake and the severed head latched onto his hand, releasing a very high dose of venom. He went into septic shock and was on a ventilator and in a coma for 5 days. He received 26 doses of the antivenom.  He is still recovering with acute renal failure that requires dialysis and is getting aggressive wound care to his hand. He has Medicare Insurance due to disability from having Guillian Barre in 2011 that left him unable to work. With Medicare he has to pay 20% of everything and it has no max out of pocket limit like most insurances.  So our portion will likely be an extremely high amount.