I haven't read TOBG girl for a long time so I can't remember the details but I know that Philippa Gregory portrayed Anne as a woman guilty of murder and incest. What we have to remember is that although Philippa Gregory does do historical research she is a fiction writer and not an academic historian. She embellishes stories. She has also admitted to loathing Anne Boleyn and to paint Mary Boleyn as a virtuous angel and Anne as some corrupt, ambitious woman who will let nothing stand in her way, is completely incorrect. I know that Gregory based many of her theories on Retha Warnicke's biography of Anne which is an interesting read, but I don't think that even Warnicke believes that Anne was a murderer.
There is no evidence at all that Anne murdered anyone or that she committed incest or adultery. I believe, like Eric Ives and many historians, that Anne Boleyn was innocent of all charges against her (which did not even include murder) and was framed. I'm sure that Anne would have been charged with murder too if anyone thought that she had committed one or that they could frame her with that too.
Eustace Chapuys, the Imperial Ambassador, reported that Catherine of Aragon's heart was black when she was opened up after her death in January 1536 and it was rumoured that she may have been poisoned. Of course, this report has led to Anne's name being muddied and her being accused of murdering Catherine, but I don't think it really was in Anne's interests to get rid of Catherine. It may have been a relief to her when Catherine died but some say that Catherine's death may have been a catalyst of Anne's fall. Henry could get rid of his wife and would not be forced to return to his previous wife.
The poisoning accusation is a very wild accusation and there is no basis for it whatsoever. It is now thought that Catherine died of heart disease or cancer and that this accounts for the appearance of her heart. Does Gregory also accuse Anne of trying to poison Bishop Fisher in TOBG? I can't remember, but this is also a complete fabrication.
I have nothing against Philippa Gregory - she writes great fiction, but that's all it is, fiction, and I do not agree with many of the theories that she comes up with. I do not believe that Anne was the vindictive, conniving woman that Gregory makes her out to be.