This is a fresh start and you are determined to do well or else you wouldn't be so scared. Breathe. Not telling others is a coping skill I use also, don't know if it is a good one or a bad one but I hope the 1 person in you family who does know can be supportive. I hope you are able to find someone supportive to whom you can confide your fears and who can help you deal with them one at a time and prepare you for this wonderful new job opportunity. If you don't have anyone IRL rely on us here.