"Take it from me, the answer is: you should always say something," Anna told Kidspot.
"Throughout all of this, our daughters Saskia, 9, and Matilda, 5, have done their best to cope with the surprise news that their mum and dad weren't going to be living together and that they'd now have two homes.
"Josh and I agreed from the day we split that the best thing for the girls was to present a unified front. We'd tell them that, although we loved each other very much as a family, Mummy and Daddy didn't love each other in that special way married people do any more, and that we were better off living apart," she recalled.
As Anna kept finding out about the different affairs, her daughters blamed her for "breaking up the marriage". She said it felt like "a slap in the face".
"Saskia has struggled more than her little sister with the break up, and she's been struggling to deal with her anger. Sometimes I can see that she's so full of rage but doesn't know what to do with it and it breaks my heart.
Her daughter has since developed violent behaviour towards her mother.
"Once, she threw a cup at my head when I asked her to pick up her shoes and it smashed against the wall. Josh doesn't think it's a problem but I've been taking her to see a psychologist to try to help her deal with her feelings."
During one of her violent outbursts, Saskia told her mother she'd destroyed the family.
"'What makes you think I broke up with your dad?' I asked. 'We've told you it was a decision we made together'."
Her daughter said she thought that because she'd never seen her mother cry about dad leaving. "If you wanted him to stay you would have been crying."
"I was shocked," Anna recalled. "If only Saskia knew how many thousands of tears I'd shed in the months since Josh left, and how I'd begged him to go to marriage counselling to try to sort things out.
"And what about Josh? I'd bet everything I have that he hasn't cried in front of the girls about the end of our marriage."
The mother admits she wanted to tell her daughter the truth right there and then but knew it was best to keep it neutral, so the girls didn't feel like they had to take sides.
"I did tell Saskia that I've cried a lot about the end of our marriage, but that I did it in private because I didn't want her to worry. And now I make sure I'm more open with my children about my feelings, so hopefully they'll learn to do the same."