Good morning @Pilbarian and welcome to the forums.
I have been a “Pilbarian”myself, so I understand the subcultures of where you live, but also the sense of distrust and resentment you speak of.
The third wheel in our marriage is an as-yet undiagnosed eating disorder which includes addictions and rituals of various types surrounding food and exercise, but has extended into other aspects of lifestyle too, with an e.d. having OCD characteristics.
The affects on the relationships, both marriage and family ar devastating, and there are times when it feels like the person is choosing to behave this way .... choosing their addiction .... but it’s not like that in fact. These illnesses are serious psychiatric disorders, like any other in that aspect, and if your wife or my husband became influenced by schizophrenia or dementia or amnesia, it would be much clearer that they had succumbed to an illness that it was beyond their control to resist.
Addictions are a coping mechanism. There is an underlying disorder of some kind, and the illness that is presenting is symptomatic of that.
While that is the nuts nad bolts of it, it doesn’t help much with the way you feel, and the thing is, you are as important as your wife is in needing ongoing support in the carer role.
I am so glad you found us. You will need other people to talk to who understand the isolation and overload that being a carer can bring, and “carer’s burnout” is a real thing.
Here is a link that may help with that.
Carer’s Hints and Tips
And here is a coffee to help start your day ..... (will appear as a triangle till approved by moderators)

@Determined @Adge