I don't know how you initially introduced the dog and cat, but if you didn't do it slowly and gradually, the result is often poor.
IF this were a kitten or very young cat it would be easier, but this is a 10 year old cat, set in his ways, stalking and being aggressive to a small dog who it sees as an intruder on his territory.
I would NOT spray the cat with water when it's near the dog. This could easily cause the cat to furiously attack the dog as a target for his anger at this.
You need to keep your dog's food and water in your bedroom, and let her eat and drink in there with the door closed. No more sharing bowls. Your dog needs to know she can safely eat.
Keep the dog safely in your room when you're not home. When you are home, do not the dog roam the house, but keep her close to you and when the cat enters the room, toss him some really great treats, catnip or toys he might like, to distract him and so he can associate the dog with good things. Stay low key. Do not yell, jump up or do anything that might put the cat in the "fight or flight" mode, since this cat is not likely to flee. IF the cat comes towards the dog in a threatening way, just stand in front the dog to block the cat.
Discipline/punishment will not work with cats who are aggressive, other than to make them more aggressive.
Cats are not really domestic, are very different than dogs and need a much different approach.