Is it normal im so uncomfortable with pornography and masterbation?

My husband and I had dated at 15 for over a year. We split up i had a 3 year relationship which resulted in a child.
That relationship ended and 7 months later found eachother again. When we decided to get married we laid it all on the table. How many people we had been with, deal breakers ect.
I wasnt too happy with the number of girls he had been with and know it was ridiculous to have expected him to be with none so i chose to except it and get married. After all, we were eachothers first everythng.. I have an extreme jealousy issue. or at least i thnk thats what it is.
I told him that i have an issue with masterbating and porn. Its such an issue its a dealbreaker. He isnt an overly sexual guy, is shy and very honest. he told me that was fine with him that those were thngs he doesnt need.
Now a couple wks ago i had gone to a girl friends house. I came home early and he didnt here me come in. i opened the door and saw him watching a porn he had hidden and masterbating. I was devestated! Like i had just walkd in on him cheating on me. He apologized up and down and eventualy i choose to move on. Then just a couple days ago i was using the internet and found pics of naked women. I again was so upset! I have such bad esteem issues and he knows that. Just the thought of him getting sexual pleasure from someone other than me enrages me. Someone tell me whats wrong with me? weve been together ten years now. Why is my jealousy of ex girl friends and the masterbating/ looking at girls bothers me so bad?