It seems a lot of men think viewing porn is fine and normal but doing what "everyone else is doing" doesn't make it right. This is adultery...Jesus said lusting after other women is the SAME as adultery. What ever we think in our minds will eventually work it's way out into our actions. Also, viewing porn is very disrespectful of women...men start seeing all women merely as sex objects. It leads to a sex addiction. As politely as possible keep talking to your husband about how offensive this is to you. You may want to search the internet for help on how to deal with this in your marriage.
Praying for you and your husband...for the Spirit to enter your lives and lead you into green pastures.