I've RTFT now and having been in a marriage with a narcissist, yes I can indeed empathise - they are malignant liars and money/power is their only interest. Plus making out the ex is the perpetrator and they are the victim. He took me to family court and I exposed him at every turn, every sitting for 4 years. I'm still married to him after 14 years' separation - he has obstructed the divorce from day 1. Let him.
Your DH
Did he have a relationship/children before you or did he live alone or with his parents?
His parents are very generous towards him and he in turn is saving for your daughter's future in ?her bank account?
This could look like purposely avoiding inheritance tax if they're not careful but that's their issue.
Has your relationship changed since DD arrived? Was she planned? How is DH with her - is he attentive and actively involved in her care/wellbeing?
I just wonder, after reading about your 2 older boys, whether DH is seemingly financially abusing you because he believes you may use 'his' money to support your sons, and that your car is on it's last legs because you can't afford to make ends meet - even though their father is a millionaire and they sound like they want for nothing.
The trouble is, if you two can't be open and honest with each other about everything then you're heading for trouble anyway. Your little girl binds you together and he is responsible for you both - as he still would be if you divorced, so why not work together?
I know it's not funny but you were married to a millionaire so does DH think you're a gold digger of sorts and he's your sugar daddy? Would he say you've got 'form' and that's why he won't share money?
There must be reasons for his behaviour - do you think he's trying to force a split and he's saving up on the quiet?
You need a joint bank account that all your bills come out of - make him financially responsible for himself and his family, not just you.