It can be very hard when your children are away from you for whatever reason. But it's more acute when it's something new and something you're not happy about.
I remember the first time I went out for the evening and left my son when he was a baby still. I was literally dragged out by a friend (who didn't have children incidentally) because it would be good for me. I had to come home after only 2 hours because I couldn't handle it. yet another person I know quite happily went away for a long weekend abroad with her husband just two weeks after having their second child and left both children with her mother. She was more worried that people would think she should stay home. We're all different and we all handle different situations in different ways.
Then there were those first few days at play school, pacing up and down, worrying that he would be upset. Rushing down to pick him up half an hour earlier than i needed too and hanging about outside waiting and peeking through the window to check he was ok...
Or the first time he stayed overnight at a friends house. I phoned lots, had he liked the dinner, phoned to say night night, phone later to make sure that he's actually gone to sleep, phoned in teh morning to chekc they'd all slept ok and did I need to come and get him yet or later as we'd agreed... but he was fine, it was me that was having the bad time!
And the first weekend at scout camp I went along each day to help out, but mostly to check he was ok!
All really really difficult but he was happy and in time I got used to it and less worried. Nowadays I can't wait for him to spend a night at a friends, head to scout camp or go to a friends for a couple of hours just so I can get some chores done in peace and/or have some me time to breathe.
I can understand your upset and that you are finding it very hard. Try and remember that the horrible feelings are as bad, if not worse, for their dad. He has to hand them back to you and only gets to see them a couple of times a week. So he will be going through something similar to what you are too. Also it's father's day tomorrow and he has to bring them back to you and spend the evening on his own which will be difficult for him too I should think. Not sure if realising that will make you feel any better or not though!
It will be incredibly hard for you until this settles into a routine. Accept that and don't worry about crying and the feelings you are having now. Gradually you will find yourself thinking about it less and finding yourself busy with other things.
My ds has gone to a birthday party today. I have 4 hours to make a treasure map, colour code 120 lollies and wrap up 100 lucky dip prizes for the PTA summer fundraiser at school next week. Will be much easier without a 'helper' interfering! And it keeps me occupied. Course I should really be doing housework and chores, but they'll keep.
Is there anything you can be doing to keep your mind off things. Open gardens this afternoon will be great. Perhaps see if you can buy a couple of plants and spend the evening working out where in your garden to put them. I can potter in my garden all day given half the chance! Can you not ask your mum to stay over for dinner perhaps to take your mind of things and keep you occupied a little longer?
Also why not look over the children's rooms. Can you use the time to have a clear out? Maybe sort out the clothes they've outgrown, make space in the wardrobe and write a list of things you need to replace with bigger sizes. Or go through the toys and books and work out which ones it's time to pack away and make space for next christmas and birthday. Both jobs much easier done without little ones unpacking everything you've packed away. Might be time to think about redeocrating your son's room too. He's probably of an age where he's keen on something specific now; cars, football, animals etc. Maybe you can work on re-doing his room a little each time he's away. Spend time surfing looking for the perfect duvet set, or picking a new colour scheme for the walls and skirting. Much easier to paint when the chidlren are at their dad's.
Cry all you like. It is hard not too. And one day, still a long time from now but coming closer each day nevertheless, the children will fly the nest and that will be another really tough few days to deal with. But it's what the children need and is part of growing up so we deal with it.
Seeing their dad is very important for them. They love him and he loves them. They love you too, and they'll be home sooner than you realise.
Keep yourself distracted best you can
Take care
Gilly