husband thinks sister is hot?

my husband was once married, i found 4 pics of his ex wifes sister, saved onto his phone when we separated. so obviously he was into her. he even watches porn about the sister in law. this was all a year ago. anyways, we went to visit my fam, his cuz was there too. i overheard them talking about my sister, saying that shes hot. now idk how to feel about this, since he had a history of being into his ex wifes older sister. now it seems like hes onto my older sister too.