Father in law is my CPA...I am uncomfortable with it...advice?

I have been married a year. I have also started a photography business and my father in law is my CPA because he has his own firm and has 24+ years experience. And it's free. But not emotionally free! He has access to everything and has taken control of all our finances and how we handle our money. My husband thinks it's fine since he doesn't know how to do it. I am starting to want to pull my hair out! He drives me nuts! I don't want him to be my CPA but I feel stuck! I'm a private person and I just feel outnumbered and overwhelmed. How can I voice myself without stepping on toes? I should also add that he loves to control everything including my mother in law.