I personally don't think breaking up with him will force him to get the help he needs. It will probably confirm his beliefs, if nothing else, and he might start isolating himself from the world.

I do agree that if this becomes a dangerous situation, you need to get out and protect yourself. You love your boyfriend, but you come first, always. If it suddenly becomes dangerous, call the police. They'll probably take him to a psych ward to be evaluated.

You should also tell close friends and family about the situation. Not just as a safety precaution, but also because you're going to need a support system yourself to help you through this.

If I were you, I would try calling a therapist and say, "listen, my boyfriend has become paranoid in the past 9 months. I'm not sure if anything has happened or not to spark this (if this is true). He refuses to get treatment. What do I do?" They'll probably want to hear all the symptoms and will probably want to start scheduling appointments with you. They might have ideas on how to get him help, while also giving you some therapy to help you through the emotions you are going through.

I was just curious how long you and your boyfriend have been together?

Take care! Keep us posted!