How would you feel?

So. My husband and I got married about 6 months ago, recently ive noticed hes staying late at work and even “drove his boss home” yesterday. Well. Today i went to sneak up behind him and hug him and he was ZOOMED IN ON ANOTHER WOMAN’S HALF NAKED PICTURE. I was so angry and felt so betrayed that I grabbed his phone and immediately blocked her. (I know probably wasnt the best response) then when i broke down crying and tried to tell him how it hurt me and made me feel he told me “its not that big of a deal”. Well it is to me. I dont want my husband looking at other women especially half naked women on Facebook. If your SO did this would you feel betrayed, unimportant, and hurt?