The source tells PEOPLE Ripa's anger is not about "about money or jealousy or rivalry," but rather about the way the situation was handled.
"Through all of this no one has been able to provide a decent explanation for why the star of the show wasn't told about a major upheaval in the program she has devoted 15 years to until the very last minute," says the source. "That's a question that deserves an answer: Why wasn't she told earlier?"
(A network source explains, "You don't tell people you have anew job until the new deal is done. She was told immediately as soon as it was signed.")
But, continues the first source: "This is a fight about respect and consideration and fair treatment. No respect was shown to the commitment Kelly has to this show, to what losing a co-host so soon after last audition process would mean, to how it would make her feel to be left in the dark and then blindsided. There has been zero attempt by anyone on the other side of this to offer a single reasonable explanation for why they would have handled it like this."
Ripa, 45, has been absent from Live! since her co-host's departure was announced Tuesday, while Strahan has carried on with the show with stand-in co-host Ana Gasteyer on Wednesday, and Erin Andrews filling in on Thursday and Friday.
On Thursday morning, the former NFL star addressed his Live! departure on Good Morning America, saying that he was "thankful" for his soon-to-be-former-co-host and the show's longtime executive producer Michael Gelman.
"I'm very thankful for her, to her, because I've learned so much from her," Strahan said. "And Michael Gelman showed me the ropes. I was so new to all of this and if it weren't for her and it weren't for Michael Gelman and the staff there that really boosted me up and made me look a lot better than I really am, I never would have had a chance to be here and I'm grateful that I'm here. We're on the same team, same family, same network."
Meanwhile, another insider previously told PEOPLE that Strahan is "hurt" by Ripa's reaction and wanted to "do the right thing" by telling her in-person.
"You can't not show up for work," the insider said. "If you're going to have a meltdown you don't do it publicly."
Though she was spotted out and about in New York City Thursday morning, Ripa has mostly been lying low, and an insider told PEOPLE the star "has gone radio silent" since Strahan's bombshell.
Live! With Kelly and Michael airs weekdays (check local listings).