Disabling chat in the on-going game is a quick way of preventing other player's misconduct from affecting you. A longer term solution is to go that players' profile and block that individual (use the gray icon which looks like "no entry" sign); this will prevent him from being able to interact with you again. If the abuse included extreme vulgarities, it can be reported at this link:
http://support.chess.com/customer/portal/emails/new
I hope this helps.
Dear Good Players,
Would share my experience and request your suggestion/opinion.
I was playing a game with [please do not name & shame users. More clarification will follow - mod]