In the absence of hard evidence on either side, you need to decide for yourself whose words are more credible. For my part, I find Mandy more credible because I can see Zak's great incentive to lie, but I can't see hers. I've decided to withdraw my support for Zak - through both my money and my blog - unless I can be absolutely certain that I'm not supporting the person Mandy describes. I wouldn't send someone to jail based on this level of evidence, but I'm not sending him to jail so that standard doesn't apply. The only things I know for sure about Zak are that he makes good RPG material and is unnecessarily combative online, and those things neither condemn nor exonerate him.