I think this has been fairly well documented.
Katie accused Peter of having an affair but was basically having an affair herself which resulted in an abortion. There is a possibility it was Peters baby, but who knows.
Her children have (all) been removed from her and she only has supervised access. Harvey was the last to go as he is clearly more difficult to place and has no father to take him. She is no "good mum" currently. She does appear to be a good mum when not on drugs and with unsuitable men, but the fact SS have removed the kids speaks for itself.
Peter Andre may not have been an angel, but Katie is the one who cannot stay in a relationship. Their relationship was already going very bad when those rows were filmed.
Emily's father introduced her to Peter, and as he knew him well one assumes he is not generally an abusive arsehole, but probably Katie brought out the worst in him.
Katie's current male pal is a user who is verbally abusive and physically abusive and banned from seeing the kids, yet she is still hanging on to him.
She has documented long term issues with alcohol and drugs.
She is very close to being sent to prison for various drug and alcohol related crimes, and is clearly not currently abstaining from drugs.
All in all I think the person starting this thread is a last ditch effort from her PR to try to paint her as an abused woman, which I'm not at all sure fits the bill...