I know how you are feeling. I return to work in about 6 weeks time. I too don't know how I'm going to cope. I live quite isolted on a farm so the nearest everything to me is 30mins away. Suddently I'm wondering when I'll find time to do groceries, am I going to be spending most of my life driving in and out of town. And also how will I find the time with the kids as when I'm not at work it will be me madly trying to catch up with the housework. I think that women was plain rude, I too wish I didn't have to return to work, and yes we could probably struggle through if I didn't but I would lose my position at my employment and when all the kids are at school it would be great to have work.
I have decided that I am going to employ a cleaner once a fortnight for 3 hours just to help out with doing the bathrooms, dusting those sort of chores, is that something you could fit into your budget? I did this when I went back after my 2nd child and found to be a real help.
I'm sorry I don't have much other advice as I'm feeling similar to you. Mother guilt is a horrible thing.