Is my boyfriend not over his ex?

Hey you guys I just need to see if I’m overthinking. My boyfriend told me for the first 5 months of our relationship he was texting his ex. This is not just any ex, this is the girl he was with for 5 years and told me he wanted to marry this girl, used to constantly tell me about how great her family is and that she has a great body and that she’s still in love with him etc. he apologized over that stuff and told me they are no longer communicating. Now we’ve been together for almost a year and recently I saw they’re refollowing each other on instagram (yes I was being nosy I know). I asked him about it and I told him I would appreciate it if he unfollowed her to show he’s moved on but now he’s making me feel like I’m being controlling and overreacting and avoids answering why he followed her again. I can’t tell if I actually am overreacting or he’s acting like a giant dick.