Many people in your writing life will not be highly skilled in the art of giving useful, non-traumatizing feedback about your work. As the primary custodian of your writing, one of your responsibilities is to protect your ability to do it. Real threats to your ongoing writing practice do exist, and one of them is harmful feedback.
When you do receive input of the wrong variety, it can shatter your confidence, confuse you and stop you from working. Usually people mean well and are simply clumsy or misguided in what they say or how they say it. Even so, damage can still be done.
Your writing may also inspire reactions from others whose motives are not so innocent. Friends, family members, colleagues, mentors and significant others often have complex and ambivalent feelings about the writers in their lives, and the feedback they supply can be tainted by envy, resentments, judgments, the need to control, the need to be overly protective, unresolved past grievances unrelated to writing, etc.
If you tend to feel vulnerable about showing your work(and almost everyone does), it is crucial that you identify the proper people to help you with your writing. Not only do you need input from people who actually have something to offer, they also must beable to offer that help in ways that are honest but not harmful. This can be tricky, because giving useful feedback generally means talking about things that need to be done better, and this implies criticism of some sort.
As a writer you need to hear reactions to your work in order to continue to improve. You need to be able to assimilate information about true weaknesses in your writing without freaking out. You also have a duty to protect yourself from well-intentioned or malevolent responses to your work that may potentially shut you down.
This may mean taking the initiative to end communications that feel wrong or damaging. You may feel like you aren’t being “nice” to them, but they aren’t really being nice to you if they damage your motivation or confidence to write. If you consistently feel bad, angry or sick after interactions with a reader, you probably need to take them out of the feedback loop.
Find the folks who want to help you, and have something to offer. And ask for the specific help you want.