I think she's always known or been fearful that hes cheated on her. I remember someone on here saying someone (thought to be Molly or mollys camp) had been messaging random insta accounts that had tagged in an event where Tommy was at and asking what he had been up to! It may have been a concert or something I can't remember! So she was obviously always checking up on him.
She's always tried to portray this wholesome family image and she's always seemed so in love and enamoured with him- so her statement screams volumes to me. She's obviously very hurt and that she's found out 'perfect' Tommy isn't quite so perfect.