Today wasn't awful after all. I survived my first day back, in spite of my substitute not having done half of what I left and was kind of (very much) counting on her to do. But it could have been much worse and I'll catch up.
DH called his mother and she came to help out with L so DH didn't have to expose him too much to the awful stomach germ. We're still holding out hope that L's yucky diapers are due to teething and this stomach thing will bypass him. MIL cooked a huge pot of chicken soup and she's a fantastic cook so that was a plus. Lunch for the rest of the week!
L remains happy despite his sour stomach and he's drinking and eating like himself. He had fun with his grandmother and still remembered me when I got home, so not so bad.
Tomorrow is the big drop off at the babysitters. He'll go about 2-3 days per week. The other days DH will have him. Then in about 6 months, I'll be off for another 8 weeks or so and can spend all my time with L and DH.
I'm luckier than many and am trying to count my blessings.