In some ways this is similar to a blog, in other ways it is not. If you have entered your email address into your profile someone can get your email address by clicking on your profile link on the site.
I don't think there's any way around this. You might consider getting a free email account from google or yahoo or something and using it just for purposes of logins. You could use it on any blog or forum and never give out your "real" email address. You wouldn't even need to check mail at the other address, just use it as a validation point.
As for being on the Internet, it's nearly impossible, if not truely impossible, to stay off the Internet. Evey phone listing is on the Internet. Public records such as home ownership, traffic tickets, etc. are on the Internet. Etc. Etc. etc.
Of course you want to be careful what you say. I'd hope you're careful in what you say all the time regardless of the way you communicate.
Jerry