All moms want to protect their children and not have the child nervous anxious or scared. But we have to allow them to figure out that they may have these feelings many times, but they CAN do this. And when they do it, they are successful.
This is just like when they were afraid to walk. Afraid to go potty, afraid to peddle a bike... We allowed them to try, to test, to fall down.. It is the beginning of learning they are a lot more capable than they even thought.
So just as you did with these other tough events in their lives.. Praise them when they do have a good day. When they do stay the whole day, when they make a new friend..
As they tell you all about their day and their good times, respond positively, but also let them know you were soooo busy, cleaning the house, running boring errands, paying bills, doing the laundry.. this will help them know you were ok without them, but also very busy and would not have had time to do the fun things they got to do..
As they get older you do not have to praise them about every little thing, but during these transition times, it is good to mention you are noticing some maturity, acting more grown up, but they will always be your little girls.
I am sending you strength mom, you can do this too..