Warning long post ahead

My husband and I have been together 3 years, married for 2. We just had a son 2 months ago, and he was born a month early via c-section. When I first got together with him he had an issue with porn. I personally was not okay with it at the time, because he was using porn instead of having sex with me. He agreed not to do it anymore, and I thought all was good. I recently found out that he never stopped watching porn, he was messaging girls asking for nudes behind my back, masturbating to pictures of my best friend, and girls that he used to love in high school. He had a Instagram account made specifically for this, and he would routinely watch cam girls. He refused to have sex with me, and would wait until he was at work or until i was asleep to do these things.. He has told me that he wants to have sex with other woman because he wants to know what it feels like since I'm his second sexual partner. He told me that he isn't attracted to me anymore because of the weight I gained during pregnancy and because I still haven't lost it since its only been 2 months since my c-section. He also thinks I'm a ugly person because I'm mean when I'm mad, and because in the hospital it was all about me and the baby and it made him feel unimportant. I have tried to leave, and haven't been able to stay gone, because my love for him has been real since the very beginning. He admitted that when he first asked me out I was basically a rebound, and he never wanted it to go anywhere. I was unaware of this, and I fell for him, hard. My mind tells me to get the fuck out, but my heart won't let me. He is trying to change, but I don't have the fight in me anymore. He keeps telling me he doesn't understand and its unfair to leave him now because he's trying. Am I wrong for wanting to leave now? I'm so lost and broken. I don't know whats real or fake, wrong or right anymore.