@Oldboy66,
The Truth is subjective, in each point.
The Truth is.. You left a wife tending to a small child alone. You are building this up to something nefarious and wrong. So let's start with you. As you were off galivanting, she's left caring for a child with no support system in place.
You left her.
And now, 4o years later, you blame her for some nights out to forget troubles and tribulations for a few hours to come back to reality of raising a child by herself. If Truth is what you're truly after, ask her how many times she cried. Ask her how many nights she's wished you were there. Ask her how many dreams she had of the future, with you in it, or the frightening realization you may not have been.
It's been 40 years. It's time to accept how your choices, and hers, have influenced your marriage.
Then be thankful you're both still here.
Cuz it could have all changed in an instant.