The only 2 that I can think of who flipped that would know anything about Bellomo would have been Vincent Fish Cafaro and George Barone. I've researched both of these guys in an effort to find out the source and truth about Bellomo being made at 21. I've read Cafaro's testimony transcript and I don't think he ever mentioned Barney specifically in that but Cafaro supposedly proposed Barney for membership so they had to be close.

http://gangstersinc.ning.com/profiles/blogs/profile-genovese-crime-family-boss-liborio-bellomo

In the link it says "George Barone, another Genovese mobster-turned-informant, later gave authorities some background on the relationship between father and son Cafaro and Barney Bellomo and the Genovese family mob. Barone said that Bellomo told him that “Fish Cafaro did not fully cooperate with the FBI” and withheld much information about the Genovese family “because of an agreement he made with Bellomo.” In return, Barone said, “Bellomo protected his son Tommy from retaliation” for his father’s sins."

My guess would be that Barone gave Barney up but I wouldn't be surprised if Cafaro gave up info as well.