My flatmate has a really horrible boyfriend, and they keep breaking up and getting back together. Every time they have an argument, he shouts at her at the top of his voice and reduces her to tears, and I don't think I can take it any longer. Today I heard them shouting, and then I heard her yelling at him to get out of our house, at which point he ran downstairs and started playing the piano, so she followed him and told him to get out again, so he poured a can of coke all over the living room. I've just had to clean it up - it was all over the wall, the carpet, the sofa and the table. Luckily it doesn't look as though there will be any lasting damage, otherwise we'd all lose some of our deposit. When I heard them downstairs I went and asked what was going on, and told him he's not to come to our house and behave like that, and that none of us actually like him. He left the house, shutting the door on her hand as he went, and she just started crying inconsolably. She said she's never been so scared someone was going to hit her. What should I do or say to help the situation? Any advice would be gratefully received!