I think what you are describing is very common fear among people about to start a new business based on their passion. So it is a common fear even without the added insult of having been undermined by your husband. I hope that realizing that there is shared humanity in what you are going through will help you find the courage to just dive in.

Also, try focusing not on self-esteem but instead on self-compassion. Look up research and meditations and Youtube videos by Kristin Neff. She explains why self-compassion is a better focus area than improving self-esteem.