I begin by suggesting you remove the other author's signature/name.
As you say, it's hard to take words like this as helpful, but the critique is not mean-spirited, and the point about not writing the three-star review is a gesture of good faith, as much as it must surely sting. ('must surely'--meaningless redundancy in modifiers 
)
I suggest you approach this with strength, patience (with her and yourself) and humility. True humility knows that you always have much to learn and many things you can learn from. Strength carries you through the hurt.
(Someday maybe one of you can quote this advice back to me.)
How many readers are as exacting as she is? I suspect very few. But getting measured against a high standard can help you.
Ironically, it's the kind of story I like to read, although I prefer a female protagonist. Since you have 8 daughters, I'm surprised at your choice of a male protagonist.
It's unfortunate that she mentioned this. It's not a substantive criticism; it's a statement of reader preference, and it can add to the emotional stress caused by the substantive criticism that follows. (And let this be a lesson to me! I sometimes do the same thing.) Put it out of your mind; it is as if a reader said, "I do so like blue-eyed heroes."
... but if I were you, I would enroll in a writing class at a community college ...
Phrased in a most unfortunate way. Perhaps it needed to be said, but, "If I were you ..." is a stinging phrase that is too damned easy to use. I'm not saying her points have no merit, though I'd be chary of expecting a community college course to offer just what I need. Her other suggestions here do make sense. I'll bear them in mind myself.
(By the way, have you thanked her? You may have to do it with tears in your eyes, but you might make a friend.)
Be aware there are 4 types of book editing: (1) The Big-Picture Edit (developmental, structural or substantive editing), (2) The Paragraph-Level Edit (stylistic or line editing), (3) The Sentence-Level Edit (copyediting), and (4) The Word-Level Edit (proofreading).
Yes, and her comments cross these lines. Moreover, her exacting standards on copyediting and proofreading may keep her from enjoying a great story. Still, you'd like her to buy it, so her exacting preferences matter.
Frankly, many of the contextual errors you make are those made by most beginning writers. ...
1) Using VERY to modify words that are strong enough to stand alone. Very is a throw-away word and has little to no meaning.
This may be true, in which case we-your-TNBW-reviewers have not been working hard enough for you. But make allowances for a character's mental voice coloring sections written in that character's PoV.
2) Using descriptions and actions as though they are dialogue tags.
Pushing writers to beats instead of tags is a common thing here. We now have one pro's opinion on the matter. We've also had contrary opinions.
3) Using too many dialogue tags when only two people are "on stage" talking. If your characters have unique "voices" we should be able to tell who is talking, either by WHAT they say or HOW they say it.
And yet ... as a reader I find I prefer to have more tags than the 'best advice' says. Maybe I'm not sure yet of my characters' voices.
Let me digress. There are several components to character voice, and there is some linkage between them:
1) Word choice (and stock phrases). (Note also that real speakers DO repeat words; in searching our vocabulary as we construct our sentences, we find most readily the words most recently used.)
2) Grammar preferences
3) Coherence of speech (topics and ideas)
4) The character's concerns and emotive state at the moment, toward first person, second person, and perhaps toward third persons.
5) The character's intent in speaking.
The first two are pretty much fixed, unless your character is drunk or overwhelmed with anger. The rest vary to some degree with the circumstances of the moment.
A reviewer who is fixated on the first one or two points will miss excellence in the others.
Erle Stanley Gardiner's characters have very similar voices on point 1 and especially point 2. We see variation most in points four and five. Gardiner was a successful writer, who turned the courtroom drama into a popular subgenre and made it his own. His plotting and clue-laying were superb. He wrote from beginning to end with almost no editing, while switching from story to story to let his typists keep up with him.
So excellence in all five of those points (and any that I have missed) is not necessary, only very desirable. And maybe if you clear a reader's minimum hurdles on all points, they will hang around to appreciate the points in which you excel.
4) Using tags other than "said," "replied," "asked," and "responded." Tags, when you MUST use them, should be invisible, so the reader doesn't even notice them. Throwing in a "he queried" or a "she chided" suddenly turns a spotlight on them. Not a good idea.
She's not alone in offering this criticism. I would strike 'responded' from her list, and perhaps add 'added' and 'noted'. Also, there are a few 'sound' tags that I consider valid, 'whispered' and 'shouted' among them. Better writers than I have used 'purred' and similar words, even though we get criticized for them. I suspect we use them where they are too easily noticed.
5) Using 2 spaces between sentences. I know most of us learned to hit the space bar twice, but such things evolve over time. We use fewer commas now and since printing is digital, all those extra spaces add up.
This lies between copyediting and production. TNBW does knock the doubled spaces out, but goes inserting spaces into the HTML it generates. (Makes me so med.)
6) Your book is longer than the norm. Yes, the Harry Potter books were huge after the first couple. But you do not have command of the English language quite like JK Rowling, who is brilliant at putting words together on a page to hold the interest of her readers--even young readers.
Was the modifier 'quite' quite necessary?
Snark aside, the norm varies by genre. I didn't find your books too long by word or page. If there's a criticism to be made, I think it's not on command of English, but on flow and structure. These are my biggest weakness, so maybe I'm projecting.
7) Your characters, in the first two chapters, are cardboard. They have zero personality, except (sort of) the black girl with the ponytail on the side of her head that your protagonist mentally criticizes, BUT she is simply bad-tempered. Your protagonist is your first-person storyteller, and he's not any different than any other adolescent male, although I love the fact that he LOVES to read. But one trait does not build a believable character.
I disagree with your criitic.
But maybe we need to make things larger than life, like stage gestures, especially when we establish characters. It's easy to fall into self-parody here. (Again, a thing for me to take to heart.)
You're probably saying, "Well, if you'd read the whole book, you'd know." But your reader wants to know and root for your point-of-view character almost from the get-go. ....
I could point again to Erle Stanley Gardiner, but she's right in general. Whether the criticism applies to you is another question.
Have strength, and strike the signature from the quoted text.
