I'm sorry that you are in so much pain at the moment. Trying to mask your anguish and keep up appearances because there are children around must be extremely difficult. You really are trying your best to manage and stay safe and really, I commend you for that. It must be so hard. I won't lie to you and say that cutting won't bring some kind of relief - otherwise, those who cut and self-harm would not continue to do so - but please, do seriously ask yourself if cutting will really help.
Any relief that you may get from cutting is fleeting and the come down after that endorphin rush almost always leaves you feeling much worse than before you cut. There are other coping mechanism out there that you can use to deal with you distress that are not harmful. What sort of things do you enjoy? Do you know of anything that used to bring you comfort? Maybe you could go and take a brisk walk outside to deal with that restless feeling.
I promise that the feeling will pass if you let it. Please do be kind to yourself.