DC’s boyfriend came round this evening, told us his mum had told him to leave etc. Initially, he wouldn't say why but then admitted they’d argued and he hit her. DC told him he could stay but I said no to DC, DC then started defending him by saying he's constantly saying how his mum is horrible, I've never met her so I don't know if this is true, said how im being unfair as he has no where else to go etc.
Am I right in saying no or am I BU?