Boyfriends and porn

Ladies, please help me out here! I'm in a rut... 
As we all know, men and women both watch porn.. I'd like to know if you ladies are okay with your s.o watching porn and or scrolling through tumblr only for pornographic images? 
I've always thought that I'd be okay with it, but ever since finding out that my s.o goes through tumblr just to look at girls with giant tits and asses, I realized I'm not comfortable with it at all:  mind you- I'm a small chested girl. It absolutely broke my heart & not to mention my self esteem just dropped to the floor. And I know this is correlated with how I view myself and I shouldn't let a man or anyone decide whether or not I like my physical body. 
But I really need your opinions on this, without judging or harassing me. 
Please and thank you, 
-fellow gal in need of advise