I am emetophobic too (I fear myself and others, but only fearing others is pretty common) - I didn't actually get on a flight until I was 30 years old, I was afraid to get in a tin box and go 30000 feet up with hundreds of potential pukers!
Eventually I had to do a short domestic flight for work, so I had to woman up. Since then I've flown a lot more, and for longer, and I gradually got less and less anxious about it. I'm now very confident I won't vomit, but I still fear it happening right beside me where I can see/hear/smell/catch it.
It has never happened. The worst thing I ever observed was about 4 rows ahead of me, a young girl with her parents maybe aged 7 or 8. They signalled the cabin crew and requested more sick bags...uh-oh. They brought her water and ice and bags, but I put my earphones in and watched something and slid as far down in my seat as I could so I couldn't see the coming and goings.
I got through it, although no sooner had I made it back to terminal I ran into the family by the escalators and the poor little thing was still hurling away into a plastic bag. That poor girl.
Anyway, I expect she was horribly travel sick but other than that, nothing!