What should i do with my cat?

Well you can take him a bath still just be careful not to get that part wet. Like maybe cover it with something. If his fur is dirty that may be affecting his wound too, so it's best to take him a bath and see how he does after that.

1. Is he eating and drinking adequate amounts of water?

2. Is his eye injured? If he can't see as well as usual he might be scared.

3. No peroxide - it kills cells, if you can get some Bacitration or any antibiotic ointment. I buy a triple antibiotic at Dollar Tree for a buck and it works fine. Put a little antibiotic ointment on it daily or a couple times a day if you see the need.

Watch his eating and drinking that's most important. I've had cats with half the skin ripped off their leg or side fighting coons or dogs and they laid around in the house, ate, drank and recuperated without a vet and are fine. Depending on where it was I didn't even use antibiotics. If it's where they can readily lick it off it's no use using it. Skin will grow back in. If he quits eating and drinking (especially drinking) then I would see about getting him help. Once he feels better he'll probably clean himself or if you just can't handle it try a damp rag.

If he's getting skinny because he's had it a while and he's got an infection internally you prob. need a vet. Cats usually run hot, but if he's unnaturally hot it's probably infected.

The cats fur seems dirty bc he is not cleaning himself, which is a sign of illness. Bathing him is not a good idea. If he has gotten into a fight with another cat, it is highly possible that he has contracted FIV or FeLV. Is the cat neutered? If not, this is extremely possible. The loss of weight and the lack of interest in cleaning himself are not good, def take him to a vet if possible. If the cat is not neutered, try looking into a low cost spay/neuter clinic in your area. Often these clinics will offer testing for FIV/FeLV. Sometimes there are rescue groups who specialize in FIV or FeLV who will also have testing sessions.

Also, I would not be too worried about rabies is the cat was in fact attacked by a possum, seeing as possums hold the most natural resistance to rabies of any mammal. It's highly uncommon for possums to have rabies.

Bathe him with diluted baby shampoo or diluted cat shampoo. if it's scabbed over bathing him will be okay, maybe shave around the area. If it's red around the edge of the scab it's going to scar bit it's healing. What's best to do is put him down actually if he's sick and you can't afford to take him to a vet.

Is your cat up to date with it's rabies shots? I hope so : /