You are wise to let the Yahoo address go away, but if this site is a value to you as it is to many, then you can always read the postings and communicate with others at your own discretion. As Aggie says, leaving gives them the power over you and you ARE above that. I wouldn't start an e-mail war as has been suggested as that will just get silly and go nowhere. You can however trace the e-mail source and report the author to their provider if the email was as abusive as it sounds like it might have been.
Lord knows there can be some heated conversation here, but it is all hopefully meant to get the thought patterns working, not to become an egomaniacal fantasy for some and a way to force you to believe the way someone else thinks is the only way. Just how many ways are there to skin a cat anyhow?

*a few lines moderated from this post- admin*