Professional wrestler John Cena isn’t letting his ugly divorce interfere with his Make-A-Wish work. The West Newbury native this week became the first celebrity to grant 300 wishes when he met up with 7-year-old Jonathan Littman of Hop Bottom, Pa. (Littman sat in Cena’s seats at “Monday Night Raw’’ and then joined the beefcake brawler on “Good Morning America.’’) The Make-A-Wish Foundation grants wishes to children with life-threatening medical conditions every 38 minutes in the U.S. Cena’s 300th wish makes him the most popular celebrity granter in Make-A-Wish history, ahead of the likes of Michael Jordan (200) and Kobe Bryant (100). “They had a nice little celebration for me at 200, and I humbly said we should do it at 1,000,’’ Cena said in a statement. “We’re just getting started… I’m just flattered completely that I could be the wish.’’ The wrestler is so popular in part because he has a squeaky clean image. Or at least he did. A lawyer representing Cena’s estranged wife is claiming that the WWE star may have been unfaithful during their marriage, and that would be grounds for her to challenge their prenuptial agreement.