I think she came across as a stronger figure in the interview than in the series.
In the show there’s a softness about her (when she isn’t full of rage), but in reality she’s tough as nails, quite bright and dodges like a politician in conversation. Which is altogether more scary.
She denies but then is noncommittal regarding the emails, she brings up things to cover herself (such as previous allegations), she shows the same jealous nastiness over women getting close to Gadd (lead actress) and towards anyone contradicting her point of view (Piers etc), she doesn’t like the comparison between the actress and herself as it isn’t compatible with her deluded sense of self, she alludes to having multiple email addresses, phones and has an encyclopaedic knowledge of dates, times, events relating to Gadd and all things baby reindeer (though it’s always a friend who told her or who saw, or she was googling for something else).
Gadd played a risky business dredging this back up and is relying on publicity to protect him. But equally it shows his obsession both with ‘Martha’ and fame, and his need to free himself of demons.