I'm another emetophobe and can also trace the source to an incident in my childhood. I deal with it better since having had cats. I'm OK on public transport and in amusement parks although I do consciously keep an eye out for queasy looking people. Whilst DP hasn't made himself ill through drink since being a teenager, if he is planning on an exceptionally heavy night on a night he would normally be at mine, he is strongly encouraged to stay elsewhere.
Don't read on if stories containing vomit upset you too much. Do read on if you are able to handle it and you would like to read about me, unintentionally, being a dick.
Once, a long time ago, I was outside of a recreation centre unlocking my bicycle. It was steel framed, quite heavy and I found it difficult to lift. This will become relevant.
A man came out with his young child. He had taken the child swimming, where the child had, of course, swallowed a load of pool water. He had then taken the child to the cafe. He had then, unwisely, decided to carry the child on his shoulders where the child was being bobbed up and down. You can guess what happened next. The child produced an absolute geyser of vomit covering the man from head to toe.
The man, who was still about 20 meters away, vaguely looked in my direction for help. I'm afraid the fight or flight response kicked in instantly and, as I had nowhere to go, I had that bike above my shoulders ready to beat him off like I'd just channelled The Hulk. The man turned sadly and headed back into the recreation centre.
I did feel sorry for him but not until a bit of time and a lot of distance had passed. Still, though, Emetophobia! Super annoying or super power?