I could be honest & just say I don't feel up to it but I feel like that brings more attention to me about why I don't feel up to it. It was supposed to be a very small gathering but now the host has invited their adult dc along too. In different times I'd feel very happy but currently I have stuff going on and don't want to face a host of nosey questions from dc who aren't my intimate friends. (as has happened previously). We only live a few doors apart.