Tbh this doesn't seem like an overly jealous guy. This looks like severely delusional behavior. If you can convince him, maybe make him see a doctor or a therapist. Justifying yourself all the time can be exhausting and pressure can be life changing. If he continues this way maybe its time to end the relationship. It seems like a huge step, and is definitely hard after such long period of time but trust me it will be refreshing and lighter than constantly being smothered by someone.
Be careful. sometimes guys like that turn into stalkers, and sometimes it gets dangerous. Call a Women's Crisis Center hotline and explain what is happening and ask how to get away safely.