I think it was reported as part of the family court proceedings - but she is quite an unreliable narrator so may well have been that she only told this to the family court to absolve herself of responsibility for her choice to have children with him up until then. I suspect the family court may well not have believed this account in any event.
And then once she did found out about his past her narrative was that she would “stand by her man” rather than being in a position to explain why she had chosen to have children and remain with someone with such a violent past. She could then explain - well I’ve known him for years and this is a shock etc etc but I know the real Mark so what sort of person would I be to hold this against him, he has changed since the and I know the real Mark. So she maybe felt it would have made her sound like a forgiving person, rather than someone who knew she was potentially taking some serious risks having children with a violent offender and remaining with him after the assault as well.
(It sort of doesn’t really matter - she stayed with him regardless and continued to have his children even once she found out and AFTER he assaulted the police officers for which he was convicted - they were clearly bonded by then. Nothing was going to get her to deviate from the path she had chosen).
(It mentioned in this daily mail article that she only found out when he assaulted the police officers in hospital -
Marten was convicted on Monday alongside her violent lover Mark Gordon of causing their newborn Victoria's death after going on the run to prevent authorities removing her.
www.dailymail.co.uk