Asking the husband for divorce

I recently got married to a man I thought I knew. But I have found out he is not the person I thought he was. He will chat different women on social medias. It used to bother me then. I got over it and tried to over look. For the past two months I was happy and we never argued as he continued doing what he always does. Then the other day he put a picture of him and a woman he met on social sites on his whatsapp. I couldn't believe my eyes. Me and him come from the same circle I felt really ashamed like he could do such a thing. When I confronted him he told me that's his page he can put what he wants. This really got me angry because I felt he has disrespected me. I decided I can't deal with him and just to ask for a divorce. My question is will my reason be valid or I will be committing a great sin. I don't want a divorce but he is pushing me to call it quits.