Amazing Analogy
It's true that FULL ACCEPTANCE of your N as someone who is mentally ill is the key to recovery. Once you give up any delusions that your relationship could be better "if only"...Once you accept that he is truly ill, you can then, and only then, begin to feel compassion for the man. (This does NOT mean you should try to reconcile. Pity him from a great distance.) Feel proud that you discovered the "real" person he is. Feel smart that you will move forward with knowledge you never had, and a relationship with another man of this type will not happen for you. You are FREE.
.... Imagine this...... You have been suffering with cancer for X number of years.
It's been a long hard journey. You've cried in pain & abject despair often...