AITAH for breaking up with my long term boyfriend over his instagram?

We are in 3 years of relation now. He has been very loyal to me in these last years. Never flirted with any girls, never cheated on me, gave me flowers, took out on dates, even introduced to each other family and had some family dinners too. One day, he wanted to add my cousin on his instagram. So, I said I will do it for him took his phone and went to search bar. I was like shocked cause it was filled with attractive and intimidating girls. Exposing themselves. I feel betrayed. I dont know if I overreacted but I cannot accept the fact that my boyfriend is looking and checking out other girls behind my back. I asked him can you stop it. He said okay I will. But few months back its same. He told me he just enjoy watching them. I felt disgusted. I told him if he is not stopping it. I am breaking up with him. He was silent and ignored me. We have not talked since then.