I am having a terrible issue. A house kitty that is let outide to be in our neighborhood came up to our door wall. My cat Mycroft went bat s**t. Osha walked over to see what was going on and Mycroft turned that aggression on Osha. This was last night. Nothing is better. Mycroft attacks Osha like it is a life or death situation. Until yesterday they were best kitty loves. He still wants to kill her. What in the world do I do? I am at a loss. They would snuggle and groom each other and now he is super mean. My heart is sad. Suggestions?