I just learned that my father died in March of 2018.

[Gymbo]

18. I am sorry for your loss

But you need to consider that he may have had PTSD and that might rationalize some of his behavior. Many WWII and Korean War vets missed the opportunity for care and treatment because the science behind PTSD is a relatively recent development.
You might ask relatives if they are still alive whether he had any of the following symptoms.

People may experience:
Behavioral: agitation, irritability, hostility, hypervigilance, self-destructive behavior, or social isolation
Psychological: flashback, fear, severe anxiety, or mistrust
Mood: loss of interest or pleasure in activities, guilt, or loneliness
Sleep: insomnia or nightmares
Also common: emotional detachment or unwanted thoughts

I realize you may not even be connected with people from the past, but there may be an underlying reason for his behavior.