WHY do I have to be insecure 😭

I have been married to my husband 3 years. At the beginning of our marriage he would only have sex with me maybe twice every two weeks. Everytime I told him I was in the mood he would always tell me he was not. Later I found out instead of having sex with me he would go to the bathroom and watch porn and jerk off, instead of having sex with me. I immediately then began to disagree with him watching it... 2 years later... he has been trying to get me to watch it with him.. I always say no but tonight i finally said yes to make him happy... so i found a video and he said... let's do it another night I'm to tired. I felt like shit... my self confidence is down the drain. The one time I talk myself into it he says nevermind. I'm not skinny like those girls.. I have stretch Mark's from our little girl... I just hate myself and how ugly I feel. I wish I was good enough for him and I wish he didnt need those girls to be satisfied... he says im no fun for not approving of us watching it together... 😭😭😭😭 I wish I was ok with it... I wish that looking at those girls didnt make me feel so bad about myself.. that he gets turned on by a skinny, blonde girl with nice boobs, while I'm here at 170 pounds with saggy boobs :(