Find a new job. Your situation won't improve unless you make an effort to change it.

Gotta love politics!

perhaps they have more experience mangering and just needed to know how things work.

Have you been in the same position for those 10 years and or showed any self motivation to up skill to be considered store manager material? I know people who have been in jobs for 10+ years too but they literally know nothing about how the business works outside of their role.

Amount of time does not mean you deserve promotion over another. Are you management material? Have you made it clear that you were even interested in a management position. I think it is important to set goals and be clear with your peers career goals.

years don't equal entitlement.

Then she was hired on as store manager and probably either has more experience or more qualifications

dick got sucked somewhere along the line

Which of you has bigger tits?

You're obviously infinitely more valuable as a Store Manager Trainer than as a Store Manager. Stick to your strengths!