The spelling of the phrase "letted go" has raised some confusion among English speakers, as it seems to be an outdated or incorrect use of English grammar. In fact, the verb "let" is irregular and its past tense and participle form is "let," not "letted." The correct form is "let go." The pronunciation of "let" is /lɛt/, with a short "e" sound, and "go" is pronounced /ɡoʊ/, with a long "o" sound. Therefore, the correct pronunciation of "let go" is /lɛt ɡoʊ/.
The phrase "letted go" does not have a well-defined etymology on its own. However, if you are referring to the verb "let go", which means to release or allow something or someone to move freely, its etymology is as follows:
The word "let" in this context originated from Old English "lǣtan", which had a similar meaning of allowing or permitting. Over time, it evolved into Middle English "leten" and "let", before becoming the modern English "let". The phrase "let go" likely comes from combining "let" with the word "go", expressing the act of allowing something to move or be set free.