Thank you for your post :) I'm sorry that you're struggling so much with this - I hope that you've had a chance to check out our other threads with people going through the same situation? There's a lot of people here who are afraid of vomiting too and it causes lots and lots of anxiety.
Have you ever thought about getting help from a counsellor? That way they can really work with you one on one which is a bit limited in what we can do here.
Ultimately, I think one of the things that would really help is trying to explore the worst case scenario. If you did vomit, what would happen? What might your friends think? For me, my friends would be super disgusted because vomit is kinda yuck, but then they'd probably ask if I was okay and help me try and feel better. For me it would be super embarrassing at the time and make me want to crawl in a hole - but then my friends are awesome so they're not going to want to run away from me. Do you think that this might happen to you too?
It's a weird question I know, but our brain likes to explore worst case scenarios even if they're super unlikely to happen - so knowing that you can face them will make the anxiety easier to bear. Chances are though that if you've been dealing with all this nausea for so long, it's unlikely that you'll actually vomit too.
Hope this helps a little