@bennyboy20 You were definitely being unreasonable. You had absolutely NO RIGHT whatever to discuss your DH's parents alcohol consumption with anyone. I would have be furious if my DH had done this. In fact DH did something vaguely similar one time, and I went off one one so bad that he never did it again.
One time I got mixed my drinks and was sick from it (some 10 years ago.) Not my finest hour, but shit happens. Hasn't happened for 10 years, and hadn't happened for 15 years before that.
DH thought it would be a hilarious anecdote to tell all his work colleagues, friends, and our family and neighbours. I heard him on the phone laughing out loud at how I was a drunken old mare, who was falling about everywhere throwing up, and didn't know my arse from my elbow. He was talking to his mate from work.
When he came off the phone, I went mad. I said 'did you seriously just tell your fucking WORKMATE that I was a drunken old mare who vomited everywhere?' He was baffled as to why I was bothered, and said 'it's only a laugh... it was funny...' When I dug deeper, it emerged her had told his brother too, AND our next door neighbour. So all the family, the neighbourhood, and HIS workplace would potentially know about it in no time. 
I said, 'ok then I will tell them about when you got so pissed that you fell out of the car into the road after undoing your seatbelt when I was fucking driving, and then rolled into the middle of the road. THEN a police car came along and arrested you for being drunk and disorderly. How about everyone at your work gets to know THAT little gem!'
'Well that was five years ago!' he said indignantly. I said 'I don't care! It's a fun anecdote to tell everyone!!! SURELY you don't mind'
'OK' he said, 'I won't tell anyone else then!' 
The damage was done though!
Within a week, I had about ten or twelve different people taking the piss out me, 'hilariously' pretending to fall about and stagger, and also fake-vomiting/dry heaving, just before bursting out into peals of LOUD laughter. Fucking hilarious.
Thanks DH you twat.
It was a good half a year before people stopped taking the piss out of me.