I am a student and I share a flat with a 38-year-old. Flat's in her name, I pay 40% but have paid extra the last two months to help her out, so it's about 50-50. Flat is openplan duplex. We both keep flat nice and tidy and pleasant and get along very well when just the two of us. She has a private bedroom, I have a balcony which overlooks the living area and have thin curtains for privacy, so perhaps shouldn't be paying as much as she has the better situation? She has ldr with fiance. He is visiting this weekend. They are both smokers. Fiance is in his 50s.
She normally smokes in her room or on the balcony. We live in Spain so the weather is lovely even now. I voiced my concerns after his last visit because he believes 'one should be able to smoke at home' and so smokes in ours. She and I agreed there would be no smoking in common areas (because it floats into my 'room').
He smoked yesterday and this morning, and after biting my tongue I finally asked him as politely as I could if he would smoke on the balcony. He just said 'we'll see'. She didn't say anything. She shortly thereafter shouted up to my balcony because I'd left crumbs on the table and then reeled off a list of things I do wrong as a co-sharer. I had a friend over and flatmate made it clear we weren't welcome in the flat, so we left. I stayed out all day to give everyone space. When I returned, the flat was smokey and their ashtray was full on the coffee table (shared area). My clothes etc are full of smoke. It just seems very spiteful and unpleasant, but I do have to live with her and they are making no indication of not smoking.
Apart from having a right not to inhale smoke, I don't like it on my clothes and bedclothes and my Mum died about 2 years ago from smoking-induced lung cancer so it's a fresh scar. She knows this.
AIBU to be really 
? And if not, how do I make this situation liveable? He will be visiting again. Sorry for lengthy post...