The 'bombshell' has been rumored for a while and dismissed by most:
https://slate.com/news-and-politics/2018/04/dino-sajudin-trump-affair-allegation-may-not-be-true.html
There are various reasons to doubt that the affair took place:
• Sajudin doesn’t claim to have firsthand knowledge of the relationship; he only claims he was told about it.
• The New Yorker states flatly that it “has uncovered no evidence that Trump fathered the child.” The woman allegedly involved denied to the AP that Sajudin’s story is true.
• The New Yorker says that reporters at the tabloid media company American Media, Inc. who investigated the story in 2015 “had questions about Sajudin’s credibility.”
• Sajudin’s ex-wife told the New York Daily News that he’s a “pathological liar” who is “infamous for making up stories” and once claimed to have seen the chupacabra, a mythical creature that kills livestock.
https://www.politico.com/story/2018/04/12/trump-love-child-rumor-media-519213
“We investigated the paternity claim and what we found did not meet our high standards for fair and accurate reporting," a Journal spokesman told POLITICO. The spokesman noted that the Journal published the McDougal and Daniels stories “in the face of substantial pushback.”
https://www.newyorker.com/news/news-desk/the-national-enquirer-a-donald-trump-rumor-and-another-secret-payment-to-buy-silence-dino-sajudin-david-pecker/amp
The New Yorker has uncovered no evidence that Trump fathered the child.
https://www.apnews.com/f37ecfc4710b468db6a103a245146172
The woman at the center of the rumor about Trump denied emphatically to the AP last August that she’d ever had an affair with Trump, saying she had no idea the Enquirer had paid Sajudin and pursued his tip.