My cat has frail bones..where can i go to find help?

[chassis]

my 2 year 2 month old Abyssinian named Morsel has super frail bones. I am talking about to the point where from the progression of his life, he's broken all four legs. His front left leg once, his front right leg twice, and his back left leg once. The current back right leg is broken with a compound fracture and it's separated.
I was originally given three options when i took him in. (By the way, the splint i put back on his leg to help stabilize the leg left sores when the vets took it off- So much for trying to help)

: i could sedate him with pain killers and give him antibiotics for the sores
2. i could re cast his leg and hope it heals -which the vets have already said that he's not going to because of the break and amount of current personal damage
3. i could amputate
4. if he breaks his rear left leg again i could either try to get it fixed or....
5. euthanasia.

expressing the feelings of this cat would be an understatement if i told you he was a happy cat. he literally does not feel the pain that he is giving himself. I'm not sure if it is him being used to the routine, or if it's because of his condition that his nerve endings dont have the proper receptors for him to respond to pain...i know he feels hurt if i tug his hair while picking fleas, so i know there must be some in there somewhere....but he tries to walk on it, he scratches behind his ear with this leg, and it's flopping to and fro as he's trying to get that itch. He cries when he's away from me (you'd think he's in pain the amount of which he meows when in a kennel to restrict movement) but when he's with me, on my lap, in the nitch in my arm when we sleep- he's quiet, smiling, puring, licking, sleeping, not moving around as he would be if i were moving.

I've raised him since before he was weined, and in some ways i blame myself. maybe he didnt get enough vitamins, or enough kitty milk. He was an orphan when i got him, and I became his mom. I'm all he's known as a caretaker, and toby- my 5 year old 1/2 x1/2 bengal has adopted him as his brother since. He loves to be held, and with the exception of his bones, he's the most loving and brave child i have ever had.

I'm having him tested for FIV+ today. I'm hoping the results come out negative.

If they're negative that's got 2 good things about it. He can't spread it to Toby, and i dont lose one or both of my boys.
if they are positive, there's going to be a breakdown somewhere along the chain of command and i'll probably be the one to fall the furthest.

What would you do if you have no human children of your own and you had two feline children that you're all they've known who needed you the most? Would you fight for them and try to solve their mysteries? or give up?

i would not like to give up. For anyone with information regarding Morsel's Condition and would like to help me research the possibility of a resolution, please do not hesitate to email me at my email address.
My sons are all I have right now. It'd be a shame to lose them when they are still full of life and love.

Thank you,
Sarah Grubb (chassis)