For most patients do not treat will suffer horrific pain and suffering. At age of 12 I had to watch my grandmother die of pancreatic cancer in the mid 60’s. A horrifying event that still haunts me.

IMO, you might want to discuss that with your spouse. If she doesn't want to have to be your representative in end of life issues, fine, pick a child. But if she does want to have that role and you bypass her you may be setting up real conflict between your child and your wife as you lay dying and afterward. Especially if your child is not her child. Better to try to have your wife understand your wishes and even if reluctantly, agree to follow them. Letting go can be the final act of love and compassion.