Dear L.,
First, take a deep breath! It sounds like you're feeling overwhelmed, which I think we can all relate to. I wonder if you took some time to care for yourself if your tummy troubles, nervousness and anxiety would be helped. If you are not happy and healthy, then those around you won't be either.
You mention a mom's group (which you say your husband recommends)- why can't you get a sitter so you can go?
My husband travels occasionally for work, in fact he just had to go 2 weeks ago for 4 days. And yes, it was hectic - between getting the baby to the sitter and our son to school, going to work, then dinner, baths and bedtime. (BTW I was thrilled that we did not order out or have fast food at all!!!) My DH arranged for the in-laws to pick up our son from school and daughter from the sitter which is something he normally does.
Here are my recommendations.
1. Find a competent sitter if you don't have one.
2. Get organized before your DH leaves. (Try to get done anything that you do that might be hard to accomplish with the kids - for example, laundry, grocery, etc.)
3. After accomplishing #1, set some time for yourself. Go to the recommended mom's group, crochet, exercise, take a bubble bath, get a manicure, whatever will calm/relax you.
You've got to ask for help and find a way to get some time for yourself.
Good Luck!
Dawn