Why would you keep someone around if you wanted someone else?

I want to be able to trust again. I don't know whats so hard about this, and why I can't just be outside of my own head. I get completely consumed by outrageous thoughts and start to believe these thoughts are going to be come reality. Maybe it's time to start talking to someone again, or be drugged again. I'm so difficult and horrible sometimes, and when I'm in those moments I cant stop. It's only after that I look back and realize how irrational I was. I blame all the problems on other people when really I do nothing to help it or stop it from happening in the first place. I want to be better and I want to feel normal. I don't want to constantly feel anxious and sick. I want to be open and fearless. I want the old me back.