In short,
Way back in 1999 Anthony got a girlfriend, Opie became a little nasty toward her out of jealously and fear of the two of them drifting.
By 2000 they had stopped talking to each other outside of the show, but they kept it running due to their huge chemistry and success. Opie was awesome at getting everyone involved huge amounts of money.
Around 2010, their chemistry began to fade, according to Opie.
2014, Anthony gets fired due to racist remarks, he expects the others to follow him to work someplace else... No one does.
The two become relatively successful in their own right. Sharing a lot of fans.
2015 - A little bit earlier this year, Anthony railed on Opie, admitting that he hated him for 15 years, a lot of people take Anthony's side due to him firing first and getting his bit out.
Opie happy that it came out, and admits they hadn't spoken outside the studio since the 90's despite being former best friends. Doesn't think they could possibly do a radio show again in the future. Is happy that Anthony came out and said it so he knew it for certain. He didn't seem to be sure, but it looks like the two have hated each other behind the scenes for a decade and a half. Although there was a lot of suspicion due to a certain text going to a wrong person.
Earlier in 2014, Anthony one time sent a text to Opie by accident calling Opie a cunt... It was meant to be a complaint about Opie sent to Norton, but he forwarded it to the wrong speed dial. As a result, Opie flipped out, and almost quit the show. Anthony was sure that Opie worked to get him fired; Opie claims the opposite, that he tried to save Anthony's job, and that the firing was bullshit. Although that's more like the misunderstanding straw that broke the camel's back, there seems to be A LOT of burn between them after years of heat.
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