You didn't get to that place overnight, it took years of gaslighting and breadcrumbing to get to that point where you have trouble trusting yourself. It will take time to go the other way too. Even if you're not always right, you have more to gain by looking to yourself rather than looking to others. That kind of repeated practice is how you build confidence.

Fwiw, I've found journaling to be helpful in learning to trust myself again. For many years I'd let things go quickly and then not think about them again. Noting things in a journal is a concrete way to not conveniently forget the truth. It's amazing how I've been programmed to move on and let thoughtless or mean behaviors slide. The journal is a semi-neutral third party that shows clearly where trust and distrust belong.

You probably already know that you make good, thoughtful decisions, so let that be your guide. In time, her influence will fade and your confidence will come back, and most likely even better than before.

This kind of abuse takes the mind F cake.