Jane,

In psychiatry, split personalities are an adaptive behaviour of the mind, a way of coping with impossible demands and stress; it's how the personality manages to survive.   M's had to try to be divine since he was 8.  He's had his father's image to live up to.  I think he's been  insecure and out of his depth most of his life. Alcoholism/drug addiction,  bullying/controlling behaviour and refusal to accept any responsibility for anything  - classic symptoms of a  person unable to cope under emotional and psychological stress.  M exhibits them all.

"Split Personality" is a widely-used term that is incorrectly and mistakenly used by people when they refer to Schizophrenia and sometimes Multiple Personality Disorder.  I'm mentioning this because it's so, so very important to be sure you know what you're discussing before you make statements like the above.  What you said above is 100% wrong.  No one has "split personalities," it's not a diagnostic term, and using it leads to great confusion and stigmas that cause enormous pain to people -- on top of their mental illnesses. 

"This story is not as unusual as it should be. Schizophrenia is one of the most misunderstood diseases on the planet. The word “schizophrenia” means “to split the mind.” This has led to a popular belief that someone with schizophrenia has a split personality. This is not the case. The split is between reality and psychotic thinking."

See the complete article at the link.

It's so very important to remove the social stigmas of mental and emotional problems, and one vital and helpful way to do that is to use correct terms when speaking about them and also to know what the definitions are in association with the correct terms.

Thanks!

Cynthia