I have no opinion on this particular case, because I generally don't believe much of what tabloids write. I think relatives, friends, ex-friends etc shouldn't speak ill of each other in front of the media, but then again, whenever I see a "he said-she said" thing like this in the media I take it with a kilo of salt and assume that at least half of it is pulled out of thin air by said media.
Now, hypothetically. I don't think a father (or mother) has to discuss it with his (her) grown-up, independently-living sons or daughters before they decide to get engaged.
I do think it would be best to inform said sons and daughters of the engagement before anyone else gets wind of it (e.g. before telling it to friends, posting it on facebook, or, if you're famous, telling it to the media). It's never nice for your sons, daughters, mother, father, etc to accidentally hear big news second-hand.