I feel horrible

So my boyfriend like a picture of his ex on Instagram after months ago telling me that he would not interact and that includes liking things on social media. I told him today that I didn't like that and he got very defensive and upset, I'm sure HE wouldn't like it if the tables were turned. Am I in the wrong? Someone please give me advice. I'm really scared that maybe they're talking again, or going to and he misses her