why am I so self conscious I have lots of problems with my SO

My fiancé and I have been dating for a couple years and we've recently started getting into a bunch of arguments. He looks up nude girls/porn you name it he looks it up .. makes me so mad because he knows how I feel about that and he can get me whenever and I've made him plenty of videos and pictures. Anyway he broke my trust and now he has the nerve to ask me to go to a nude beach with him like wtf. We have a 6 week old son together and I'm not looking my best but give me a break I had a baby. Your not supposed to have sex until now but I have done it since 2 weeks post partum so he wouldn't leave me he's addicted to sex we do it at least 1-3 times a day not including blow jobs. When we're on walks or doing things he stares at other girls asses which is normal I guess but makes me so mad. Maybe my hormones? I just don't like feeling like the other woman like I'm less important than porn or women on the street. Anyone else have this problem or know what helps?