Enclitic pronouns are usually only added to the infinitive, gerund and imperative forms of verbs. However, as explained in the Nueva gramática de la lengua española (Section 16.7e),
[...] No obstante, la enclisis a las formas personales del verbo (díjolo, violas, contestole) se documenta hasta el siglo XX tanto en el español europeo como en el americano, con más frecuencia a principio de oración o tras pausa. Aún se usan ocasionalmente en la lengua escrita, sobre todo en la literaria, formas verbales conjugadas con pronombres enclíticos, aunque suelen percibirse como arcaizantes. [...]
i.e., enclitic pronouns added to personal forms of verbs (like the preterite) were common in Spanish until the 20th century, and are still used in written, literary language, though they are considered old-fashioned. They are correct, but you would not use these forms in everyday language.
Note also that "confesome" does not have an accent, as the stress is on the second to last syllable, and the word ends in a vowel. See here for the complete accent placement rules in Spanish.