I have had "Don't you know how ancestry works? You're supposed to do it all yourself", also "I can't possibly be related to someone like you" and last but not least "you're delusional! you have fabricated the documents for your Dad's death as you can't bear the idea he has another family and abandoned you".
I know exactly what you are talking about.
Last year I received this message - "CHECK YOUR SOURCES!!!!!! MRS FIRSTNAME LASTNAME IS NOT DEAD!!!!!!"
I replied - "Well, seeing as she had a massive heart attack at the Bowls Club Luncheon in front of 60 people; and seeing as my wife gave her CPR until the ambulance arrived; and seeing as she was declared Dead On Arrival at West Suffolk Hospital; and seeing as my wife had to register the death as her husband was in no condition to do so; and seeing as I have her Death Certificate in front of me as I type; and seeing as I attended her funeral; and seeing as the husband visits us every week and is still grieving 20 years later; I can tell you this - My tree is right and your tree is wrong."
She replied - "DON'T BE SO NAIVE AND STUPID. DON'T YOU KNOW THAT DEATH CERTIFICATES CAN BE ALTERED AND FORGED?"
I replied "I will tell that to her husband and let you know what he says."
Needless to say, I did not tell him. Last I checked, her tree was the same.
Regards
Chas