You could try to bend it straight, but it will be less stressful if you just let it heal. You also run the risk of damaging it further if you try to straighten it. Plenty of these cats have upturned noses from ramming their tanks. I doubt he'll fail to recover. Most of the damage is internal and you really can't do much for it. Just let him rest and heal up. If it were my fish, I wouldn't be adding any salt or changing the temps. If your water is already pristine just let him heal.