Learn Spanish (Latin America): Se me soltó el jarrón frágil y se me quebró. - I accidentally dropped the fragile vase and it broke.

Using yo solté sounds completely intentional, as if you purposely let go of the vase. The se me structure is the "accidental se." It translates literally to something like "the vase released itself from me." This shifts the blame away from you and makes it crystal clear that it was an accident.

If I am the one who accidentally dropped it, why is the verb soltó instead of the "yo" form (solté)?

In the accidental se construction, the thing being dropped or broken is the grammatical subject, not you. Since el jarrón (the vase) is a singular "it", the verb must be in the third-person singular form, soltó. The indirect object pronoun me is just there to show who was affected by the action.

I learned that se me cayó means "I dropped it." How is se me soltó different?

Both can translate to "I accidentally dropped it," but they highlight different parts of the accident. Caer means "to fall," so se me cayó focuses on the object falling. Soltar means "to let go" or "to release," so se me soltó emphasizes that the vase slipped from your hands or escaped your grip.

Why is se me repeated before quebró? Couldn't you just say y se quebró?