May I suggest some thoughts.
Are you or were allowed to send money to someone in prison, I thought you could only "spend" what you had earned.
Attitudes were different then to disputes between husband and wife, would threatening your wife result in a long custodial sentence, or would it just be a domestic with a policeman having a firm word with the offender.
Is it possible he he had a breakdown and was committed to an institution, in those days once in it was hard to get out again, a common threat in my youth was the men in white coats will come and take you away and you won't get out, it was not without some substance.
Mike