Originally Posted by
Jaguar55 
Defending myself from his attacks and insults is exhausting. His absolutely freaky nonstop paranoid obsession about cheating is bizarre. He's been on this kick now for 18, maybe 20 months. And I've spent most of that time trying to reason with him and prove my innocence.
Reasoning and explaining are only going to get you exhausted - it hasn't made a damn bit of difference, has it? I agree, detaching from this cycle looks like your only way forward. XAH used to do something similar. I finally decided to stop engaging with his nonsense when he started - just said nope once and let him get on with his ranting. I didn't react to him at all. Co-dependent No More really helped me with this.
A word of caution though. XAH was controlling and verbally and emotionally abusive. I didn't see it at the time though. Detaching in my situation just aggravated his anger and made my situation much, much worse. Please be aware of this and if you find yourself in the same spot, call a domestic violence (doesn't need to be physical abuse) hotline for advice.