The phrase "sold down river" is a colloquial expression that suggests betrayal or abandonment. Some antonyms for this phrase could include "supported," "loyal," "committed," "reliable," "dedicated," "devoted," and "faithful." These words suggest loyalty and trust, as opposed to the negative connotations associated with being "sold down river." Additionally, words like "upheld," "honored," and "respected" indicate a sense of dignity and respect, where the opposite of being betrayed is being upheld and supported. Overall, the antonyms of "sold down river" reflect a sense of trustworthiness and reliability, which are the opposite of the feeling of abandonment and betrayal that the phrase implies.