Sounds like a father who is worn out by all the misery that has been brought into their lives. Sick to death of adult kids who are still sooking whining and blaming everyone else for poor life choices.
If only fathers wrote letters to his skids in defense of the step-mother, would love to see that, hey I've got an idea I will draft a letter for DH and get him to send it to the entitled skids - as if that would ever happen- at least the father who wrote the letter has balls of steel- looking after himself and his wife from further turmoil- he is 100% man in my eyes.