boyfriend watching porn

me and my partner have a 5 month old and obviously we haven't been having sex as much but i always try to as much as i can, and the other day i woke up and i could hear him kinda moaning so i put my head out the door and he was having a wank while he was using the 'toilet' and it instantly just made me feel sick, does anyone else think it's wrong?? like the fact he's wanking to some other women makes me feel physically sick and not feel good enough, and i don't want to sound overly stupid but it's making me depressed that he's doing stuff like this, and since i haven't had his facebook/instagram he started following and adding girls and sex pages and i know he wasn't following them before, i don't know what to do and i have spoke to him but he never takes me seriously