We cannot avoid this. All writers need the test readers who get to see the manuscript in its early stages. It is far from perfect but you cannot make it better without their contribution. And you receive criticism. And it hurts.
Here are a few reasons why it is not the end of the world. And, really, don’t burn that manuscript just yet.

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Remember it is subjective

You will never please everyone. No author can do that. Whatever critique you receive, keep in mind the fact that it may be justified but there is a chance the criticism has nothing to do with your writing.
You wrote a public announcement you are looking for beta readers. People wrote you emails and you sent the chapters.
Maybe an underage person volunteered to read your cosy mystery about an old man feeding pigeons. A more mature person could enjoy it more. The teenager may lack the ability to relate to the elderly. Or understand the bitter jokes about life.
Maybe a person attacked by a bear got interested. And there is a bear attack in your novel but you did not mention it in your brief description in the announcement. This person may dislike the book because of the painful memories, not because of your writing.
Remember, you cannot fix all your betas pointed out.

Let it sink

Writing is an overwhelming activity. And the authors are often burdened by their full time job, family, and other issues. The final stages of finishing the latest version of the manuscript are especially demanding. Did you manage to get four readers eager to help you?
Good job!
But are they sending the chapters back all at the same time and you are working on the changes and navigating through the next chapters?
And there are so many things the readers pointed out and you already see the following sleepless nights?
Did somebody say something particularly ugly? Something you really, really don’t agree with and you don’t understand how it could happen the reader did not get what you were trying to say? Of course your princess has delicate hands and weak voice! Not every female side character needs to be a tough warrior.
Even better, the other reader said the issue is perfect and well-written but pointed out another huge problem? Now your male protagonist is unacceptable because he should have given that poor child those money.
And your third and fourth reader hate the whole two chapters. How did you dare to kill that side character? And why did the protagonist lose that fight?
Dear reader, I imagine you feel nauseous after this paragraph. Yep, criticism can be very confusing. You are doing your best and your readers just don’t understand what you wrote.
But they may be right. You just need to close everything and go for a walk. Do not come back to it for two days. Watch a movie and eat a good dinner.
And then open the feedback again and you may see the criticism was at least partly right. And after the rest, you are ready to decide what changes are needed.

Do not rely on one opinion too much

It is always good to get more than one opinion. One person can hate when your character discusses that planned murder with the blind dog. Other four people can love it, even relate to the murderer. One person can throw your manuscript away because there is a homosexual elderly lady who grows geraniums. Others may say there is finally a great role model character. But they still hate the dog. And the murder needs to be punished!
Apart from this, if you happen to meet a person who does not criticize your work but loves it, you both may fall into a trap.
You started your work as a thriller but this supportive person genuinely enjoys the kitchen scenes and descriptions of meals. Well, you may love their critique and write many, many scenes about cooking. The person loves it, cooks all the dishes and sends photos.
The novel must be great… Or maybe not.
Try to find several elements in your work the people seem to enjoy. That means, having enough readers.

Thank. Almost always.

Reading someone’s unfinished work is not easy. The story can be full of plot holes and inconsistencies. The style is far from developed. And sometimes… Grammer? What is Grammer? (typo intended)
All the beauty you have in your head is not materialized yet. But the readers soldier on, try to help, search for the great parts and the bits with potential. And point out the issues that need more work. Many times, a lot of work.
You may not agree with the final feedback. But you should remember all the free time the reader has spent with your words. And say at least thank you.
However, the world is a dark place. And there are rogue “readers” who do not try to help. They rain negativity on the sensitive, fledgling authors just for the fun of it. Or to boost their own ego. Harsh criticism may be deserved sometimes. But what if insults and vulgarisms land in your mailbox? What if the reader calls you names, or makes up other insults that are not even connected with your work?
Trust me, sometimes you can stumble upon a dangerous, toxic person. I know a writer who was even harassed by sexual comments in the feedback. Do not say thank you. Report and block. The end of story.

And what about you? How are you dealing with criticism?