Again, it is not MLC. Your W's entire life has been one trauma after another and her current state is a result of all that built up unresolved issues. MLC is a 'perceived' need that something was lost in life and they are trying to regain it.
"I believe there have been 2 triggers of her Father dying almost 3 years ago which she has never got over and going back to work full time 1 1/2 years ago instead of being a stay at home Mum."
No this started way before when she first moved in with you when you were kids. No child should have to go through that trauma.
"are you saying that I have to fight against her beliefs that are stronger than some other peoples and that to prove I've changed will take longer for her to truly believe?"
No. I'm saying that you have to find a way to change her beliefs. That's why validation in DBing is important. Fighting her is telling her she's wrong. Changing her is saying things like 'I see why you would think that way". Rather than battering her defenses which is just going to make her fortify them more, seek weaknesses around it.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.