Facing repeated questions about his future, McGhee said: "I'm a realist. I've been in the game a long time and I know how it works.
"I've left lots of football clubs for different reasons. It's generally been my own decision, whether it's leaving to go somewhere else or coming to a conclusion with people around me that it was time to leave - and you know when that is.
"I certainly don't have that feeling at the moment.
"You have a feeling in your stomach that you don't want to come in here or that you can't face walking out in front of the crowd.
"The day I have that, I'll know it's time up for me."
Aberdeen sit ninth in the Scottish Premier League, with 10 points from 11 games and McGhee's record of 17 wins from 57 games is under increasing scrutiny from disgruntled fans.
"There will be strong feelings out there about me and about the team and about the club," he continued.
"The fact is I'm still here.
"All I can say to the supporters is that we are hugely embarrassed by what happened on Saturday.
Highlights - Celtic 9-0 Aberdeen
"I will continue, in my way, to do the best that I possibly can to get a result against Inverness on Tuesday and to eventually claw back some sort of respectability.
"I would never have dreamed that a team of mine could lose by a scoreline like that. I take a huge amount of the responsibility for it.
"Saturday highlighted, regardless of any circumstances, how much work is still to be done."
McGhee refused to speculate on whether Tuesday's game was a must-win for him and would not divulge his thoughts on what had gone wrong against Celtic.
"The most important thing for me is the Inverness game," he continued. "It's a good thing that we've got a game tomorrow to bounce back. It allows me to focus on that and not concern myself with what everyone else is thinking.
"We have another three points to go for on Tuesday and I believe that we have a team in there that, if we get it right, can beat Inverness.
"The reasons for me saying that are only going to sound empty on the back of the result, so I don't think it's necessary or constructive to try and explain why I feel that.
"We could play the best we have in 10 years and lose 1-0. There are all sorts of dynamics in football. Likewise we could win 6-0 and doesn't really change a lot. We'll play the game then reassess."
Asked if he considered stepping down over the weekend, McGhee said: "I have a belief in why we are where we are and at this moment. I'm entirely comfortable sitting here as manager of Aberdeen.
"The fans want to see passion and commitment in every situation, in every area of the field, every week. If we do that often enough, then I'll have the opportunity to explain what happened at Celtic Park. But only from a recovered position."
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