Older Cat Almost Died

I have an 8 yr old neutered male Russian Blue who recently lost his female companion. I brought home a 4 yr old neutered male tabby. They were together for about a month and didn't fight but I noticed that the new cat would chase my older cat whenever the older one tried to go from room to room or go to get food or water. They didn't fight. My older cat would always retreat. Finally, my older cat got so dehydrated that he had to be hospitalized. I almost lost him. Now I have them separated and am scared to reintroduce them. I had originally thought that they would "work things out" for themselves and that everything was OK since they didn't fight. Help! What can I do to keep the new little bully from making my older cat starve to death? Should I bring the new one into the room but squirt him with a water bottle if he tries to approach the older cat? Or would this cause "bad vibes" for one or both? Most people are telling me to just get rid of the new cat.

It may take another re introducing. Sometimes when you seperate them and let them sniff under the door, they will know each other. I would do it for a few weeks, then watch close when you let the other out. Squirting for that usually does not work. It may just teach them to stay away from each other and then when they come into contact, it may be worse. Keep gradually introducing them and see if it works.