Not sure about whether this sentence is necessary

[Mountainbreeze23]

The author narrates three occasions when 'time stopped' for her: moments of epiphany when she had to do something life-changing. Each time she decided to do a Misogi.(The author narrates three occasions when 'time stopped' for her: moments of epiphany when she had to do something life-changing each time she decided to do a Misogi.)
The correction says that the sentence 'Each time she decided to do a Misogi should not be a sentence on its own. I meant that each moment of epiphany she decided to do a Misogi. So, shouldn't this be a new sentence ( the way I had written it)? Confused, and I would like some clarity on this.

[Juliet+1]

Well, that "correction" is definitely wrong. But your sentences are not very clear, so maybe there's a misunderstanding. The colon between "her" and "moments" is a real show stopper.

I'd rewrite it like this:
The author narrates three occasions when "time stopped" for her. These were all moments of epiphany when she had to do something life-changing. Each time, she decided to do a Misogi.

[Mountainbreeze23]

Thanks so much, Juliet

[Helen Akoth]

The author narrates three occasions when 'time stopped' for her: moments of epiphany when she had to do something life-changing. Each time she decided to do a Misogi.(The author narrates three occasions when 'time stopped' for her: moments of epiphany when she had to do something life-changing each time she decided to do a Misogi.)
The correction says that the sentence 'Each time she decided to do a Misogi should not be a sentence on its own. I meant that each moment of epiphany she decided to do a Misogi. So, shouldn't this be a new sentence ( the way I had written it)? Confused, and I would like some clarity on this.

I agree with the correction. “Each time she decided to do a Misogi” is not a complete sentense, and therefore, should not stand on its own. That is what we call sentence fragment (treating a dependent clause as a complete sentence). There are many ways sentence fragments can be corrected. One of them (and the simplest approach, by the way), is by joining the preceding sentence and the dependent clause using a comma. Like in the case above, doing this should correct the error:

The author narrates three occasions when 'time stopped' for her: moments of epiphany when she had to do something life-changing, each time she decided to do a Misogi.

Notice how I have introduced the comma. I hope this helps!