This is not going to end well.
People are resistant to change, and that includes people who change themselves through self-improvement. You're on a path where your personality is going to be transformed and she isn't going to like it. She's going to want you to remain the submissive doormat that you've always been. You can try keeping the relationship intact, but it's going to have to take all of your will power to stand up to her.
I just bought a very nice Volvo S80 that is going to be my project in the months ahead and as I was expecting, she got really annoyed and pissed off when I got home.
My response: "Be a good girl and maybe I'll take you out for a drive in this beautiful state-of-the-art piece of machinery!"
"Why have you ruined something great that we've built up over 6 years?"
My response: Meh... I needed some excitement in my life. It was either a car or a threesome. I chose the car.
"Are you really choosing a car over your family?"
My response: This car is your new adopted son. I urge you to care for him as you would your own child.
"I invested my money to be able to earn more money!"
My response: I'm proud of you.
Since we (this family) now has two cars, she has decided to sell her car because, as she said, "I don't need a car, do you understand?".
She has, in the past, told me that she'd sell the car as a kind of punishment towards me when she was mad for some reason. I got sick and tired of that and that's also one of the reasons I wanted my own car.
My response: If you don't need it, then by all means sell it.
You can't let her little temper tantrums and guilt trips get to you. Just pass it off or respond with something humorous. If she gets even madder, turn it up a bit and add more humour. She'll either crack a smile or storm off. Let her react however she's going to react.