Harvey dislocated the elbow on Saturday night against Richmond, and will undergo surgery this week to repair torn ligaments on both sides of the joint.
"He's shattered," teammate Drew Petrie said on Monday morning at Ascot Vale Leisure Centre.
"Being his first year as captain and he's going to miss the next three months, it's disappointing for him but I don't think he will drop his head around the club.
"He'll still have a major role to play around the club this year.
"I spoke to him last night and he said he would be out for 10 to 12 weeks, which was Dr Con [Mitropoulos]'s prognosis.
"Brent reckons he'll be back in about eight weeks because he's going to try and get back early. With his little bones and little ligaments, he thinks he should be able to heal pretty quickly."
Petrie said Harvey would be tough to replace.
"It's a very big loss, with [Daniel] Wells and Matty Campbell injured as well. They're the quickest guys in our side," Petrie said.
"It's disappointing that those three won't be out there this weekend, but in saying that, it does open the door for the young guys to show their worth."
Defender Lachie Hansen will miss at least three weeks with a hamstring strain sustained against the Tigers, while Wells (hip) and Campbell (hamstring) are rated only outside chances for Friday night's clash with Collingwood.
Petrie said the loss of Hansen meant the Roos would have to look at reshuffling their defensive half, with solutions possibly lurking in the lower league.
"You look to blokes to come in from the VFL. They're the ones that are going to keep the senior players honest this year, so if they're pushing through, it's a positive for the club," he said.
"Shannon Watt played well yesterday at North Ballarat and Nathan Grima, who came back from a knee reco last year, played well for Werribee, so we've got guys ready to go."
