Dealing with severe paranoia: seeking advice

I’m nowhere to this extent, but I do have minor episodes of paranoia around people breaking in my apartment and stealing from me or attempting to 💀 me and I can normally fight that away with rational thinking now I’m in a better place. I normally make sure all my windows and doors are locked before I go to bed and I keep a knife at my bedside. Sometimes when it gets bad, I’ll have to search the house with my knife, although I really try not to as that is validating my fears. I also have a little dog who helps me with rational thinking in this situation. When I get into it (typically at night), I have to tell myself that I locked all the entrance points in the house and I haven’t heard any knocking or glass shattering to signal those entry ways have been opened. If that doesn’t work, I know that my little Pomeranian wouldn’t let anyone in here without making a racket! He always sleeps with me on my bed or right next to it so I know that if someone would bother him, I’m the first person that would know. If he’s sleeping next to me or laying with me, there is no problem. Though, I used to be so much worse a couple years back where I was convinced my father was going to 💀 me and I have snipers outside of my school that he was friends with (ex-marine and ex-army). I was also convinced that all my friends were out to get me and report back to my mother while I was going through trauma and never trusted anyone and was very very secretive. I at one point learned how to write in code for personal notes and I would hide them around my room. Once I was done with them, I would actually tear them up and eat at least half of it so you couldn’t put the pieces together even though it was in a complex code. I wish I could remember how I go out of that, but I have severe memory issues and most of my life is blocked out.