That is a statement that seems to pre-empt, rather than to respond. I think a factual under-reaction would be the most assertive thing. If he asks where his things are, tell him they're in the cupboard and don't get into it further, whatever tone he uses, whatever accusations he throws or explanations he demands. I think he knows full well he can have his own stuff in his own flat if he wants it. You don't need to tell him that. Or arrange it for him. I guess he might make all kinds of critical assumptions about your motivations and the temptation is to defend yourself against what he believes about you by explaining yourself, or even to pre-empt what he might think by presenting it to him in a particular way.
My IC taught me about assertiveness and not having your buttons pushed too. I remember JADE which means you never Justify, Argue, Defend or Explain. It means you stick to the facts, answer a question once, then end the conversation.
And is it the front bedroom? Or is it 'my bedroom' and 'my chest of drawers' and 'my wardrobe' ?
