He stopped any kind of drinking after his brother’s death from alcoholism.
But you are correct Trump has stated he has never drank.
He has also stated he stopped drinking with Fred’s death.
It’s a conflicting statement, but not controversial. I presume he means he never drank as an adult.
Can’t find anything that backs up your assertion that he stopped drinking after his brother’s death.
“It taught me a tremendous lesson. ... He said, ‘Don’t you ever smoke. Don’t you ever drink.’ ... And I’ve never had a drink and I’ve never had a cigarette. Those are the good things [about me]. I don’t want to tell you the bad things,” Trump said.