Au pair has been with us for 5 months. She is a really nice girl and good with the kids. We've just been on holiday for 2 weeks. I paid her for when we were away and also lined up a weeks work with a friend so she could top up her income. We have some house rules of no smoking ( not that she smokes but previous Au Pairs have)in the house and also I asked when we were away that she didn't have any visitors as I wasn't comfortable not knowing who was in my house. She arranged for a friend to visit when we were away and said the friend was staying in a local b and b and that they were going to explore the UK for a few days.
Anyway, back from holiday today - house stinks of fags and the spare bedroom has clearly been slept in. I am seething.....AIBU ? I don't know what to say or do...