The N's paranoia, out of control

I tried again. The holidays were here recently and it felt right. Even though I knew it could end at any moment with him leaving like he does every three months and disappearing I took him back. I believed him, but then started to question him about it more and more. He became infuriated. Then all of a sudden the tables turned quickly on me. Turns out he then asked me who **I**was "*^cking last week because he has audio recording that he implanted on me at home. Three month mark was here: he left the next day this time because I told him he had to leave because of the outrageous accusations and threats plus he said he was leaving anyway-again. He later went on to tell my mother and let her listen to the audio recording. Turns out that the audio is only the TV. Because I NEVER CHEATED. All I do is run around town shipping for groceries, taking care of our home, and making sure he has a nice home cooked meal every night. He has gone on and on making up a story line about something I never did and tells a story like you wouldn't believe. If you didn't know him you'd orobably believe it. The only one who has cheated, been dishonest and lied has been him. I've been constantly accused of cheating, I've been verbally abused and now that I won't let him back in the abuse is worse. When I agree to see him and he has to leave I'm called a fat pig, a whore, and he threatens me telling me he will find someone else better. I'm tired of this. Why can't I let go? Do I have a self esteem issue? What is wrong with me? I feel like I'm under a spell. I know this is all wrong for me and my son- so why ant I quit him?