Take a step back from the whole situation for a minute. What I hear you describing, is a man who is WAY beyond the ordinary craziness of the Walk-away spouse (and yes, they can be pretty crazy at times). But your fiancee sounds mentally unstable in a much more serious way.
Does he have any history of bipolar disorder? (Sounds manic). Any history of substance abuse? (Meth makes people manic, paranoid, etc). Any history of thyroid disease? (High thyroid can cause psychosis). Any other health problems in his history, or his family history? (Huntington's Chorea?) Has he been using Chantix to stop smoking? On any other prescription meds? Does he have OCD? Could he have a brain tumor?
I'm just telling you, both as a physician and as someone who has been on these boards for forever - it sounds to me like something more is going on here than even the usual crazy shenanigans of the WAS.
Step away from it, get your feelings out of the way for a bit, and just see if you can figure out what's happening to him. The inappropriate postings on FB have me worried. Oh - and be safe, please. He sounds dangerous in his current state.
