Easier said than done. Especially when they keep deliberately posting lies about you and follow you around the internet looking for other places they can harass you.
You can choose to tap into your gold mine of knowledges and the wish to help and relieve others sufferings and make greatness out of it, or polute your mind by plunging into these debates that have reached the point that they do not benefit neither the readers, nor you.
My prescription to you HV:
Practice being aware of every thought that comes to your mind and from there make a choice. If the thought brings greatness and happiness out of you, entertain it. If not, do not feed it and it will die on its own.