Jo would deal with her own feelings of betrayal from her supposed close friends at a later time. Right now, all she could focus on was the fact that Meg was here. She and her mother had been murdered by this demonic bitch and Jo felt that it was time she had a little bit of payback. She knew that she should pull back, calculate each move to do the most damage, but the mixture of pain and fury was pushing way too much adrenaline through her and a red haze of anger was starting to be all that she could see.
When Meg started saying what she did about Sam -- reminding her about what happened when she was controlling him -- Jo crouched to grab two of her new knives and then launched her entire body at Meg. She wanted to make her hurt. Make her bleed.