I see that managing criticism is one of the things you are not sure how to do at this point. It is understandable. A lot of us are not able to learn how to receive and respond to criticism. One of the things that happens is, we tend to take criticism as a negative message about who we are as a whole person, instead of maybe receiving it as a message or feedback about one aspect of us or any of our behaviour.
For example, when someone tells us that we do something the wrong way or that we speak a certain way or look a certain way - one of the reasons why it becomes hard for us to tolerate that is because we "hear" that as "I am not good enough as a person". And this makes us feel terrible about ourselves as a whole. Instead, if we are able to focus only on that as "feedback" or information of one aspect of us, or behaviour of ours, we might be able to receive it better?
Because at the end of the day, none of us is perfect. We are all, as a norm, fallible (as in we make mistakes and things go wrong).
So the next time someone says something about you, I'd encourage you to think:-
1. What aspect of you is the information about? or what behaviour is it about? (this will shift focus from you feeling bad about your whole self)
2. Do you find that information relevant for your growth or progress? If you do not want to work on something or change something about yourself at some point, THAT IS OKAY. You have the right to choose what feedback you want to receive (and act on) and when.
Now, about responding to children's questions. Well, children's curiosity is amazing. And yes. it can be such, that it can get difficult to manage at times. I am wondering, what part of it do you find difficult? First of all, you do not need to give them information that you think might not be necessary or appropriate for them to receive. There are ways in which you can respond, by telling them just what is necessary for them to know, for their well-being in that context. And that is okay. Secondly, is it that you find it necessary to answer all their questions? Why is it so? Maybe you don't need to know (or give) all the answers...Yea? Answer what you can, and for the rest, you can wonder with them. This lets them know that they have the freedom to question and wonder (which is important for their learning and growth) and that they can do so with you. They can also see and learn from you then, that it is okay and natural to not know all the answers and that we could try and find them, which could further encourage self acceptance and quest for knowledge.
Cyber bullying, well, that is a form of harassment, and also considered a criminal act under certain circumstances. Please make sure you are able to safeguard yourself, and take the right steps to ensure cyber safety for yourself and children under your care.
Hope this gives you some direction.
Take care and best wishes,