If you sell the site, and the new owner does not change the content, they will share the guilt - but the date of purchase will show you as the 'lead', and you are responsible for your own actions.
If you think that hiding your identity will allow you to attack someone via your site, be warned that if they have a decent lawyer, and money, you will not escape the law.
Harassment and libel are just as deprecated on the web as they are in the real world, and - often - much easier to prosecute.
I'd worry less about the security of the site, and your name, and more about being able to justify the comments that appear on your site.
Is it 'defamatory' or fact? Can you convince a judge?
If you are justified, then 'free speech' goes a long way ... but if you cannot justify the comments, then it's long past the time you needed to be paying a lawyer.