So sorry your wife is going through this. My mother was told by a nutritionist (and I've seen it mentioned on this site), that's she should try very small amounts as often as possible - the stomach can't hold that much at this point, anyway. And yogurt was a great thing, too - and Ensure. As for anti-nausea meds, if you have a good prescription plan (they're very expensive!), you may try getting several different ones. My mother had Zofran and 2 others I can't remember, and she found that one would work on one particular day, then she'd have to take a different one another day - we just juggled the different medications.
Best of luck to you and your family - much hope and hugs going out to you,