My experience as a nurse in NZ hospitals, is that if you clearly state that you do not react well to Morphine, they will not use it.
Fentanyl via PCA pump is often used as an alternative. It doesn't tend to cause the same problems as morphine, i.e the hallucinations, nausea, vomiting.
This is definitely something you need to discuss with the Anaesthetist , they will prescribe the post op analgesia.
Just be very clear that you do not want morphine. Kris has the same awful hallucinations and would never have it again.
Maybe you could Google Fentanyl and read up about it so that you can have a robust discussion pre op with the anaesthetist. Actually, tell everyone you come into contact with at the hospital when you are admitted or at pre admission clinic. I can guarantee they won't use Morphine.
Tammy