Your partner sounds awful and has said some really insensitive, even cruel things. You would be better off without him.
However, I don’t think he is entirely the whole problem. OP, you sound like you have very low self esteem, even without him being involved. Many of us do. It’s not a criticism, but a compassionate observation. It’s a tough place to be and I’ve been there too. But Love for yourself comes before any successful relationship, and you sound like you are currently suffering from hating yourself and are obsessively criticising yourself.
Right now, instead of working on that within yourself, you are forensically examining your man’s opinions of women to prove your own opinion of yourself. You are desperate to get reassurance from him, (while really you need it from yourself first). It feels like you are almost obsessively trying to prove that he doesn’t want you. Eg, buying him a massage as a test? You are worried about him finding other women attractive, so arrange for him to be stroked all over his naked body by another woman…. Then, I’m guessing, you quiz him relentlessly about how it felt/ what he thought of the woman until he says something that upsets you? Then it becomes a devastating injury….? And throughout, you reject his constant insistence that he finds you attractive … instead you trawl his internet usage to prove him wrong….
So let’s clarify this. You have every right to expect your partner to be respectful of you and other women, to be faithful within the boundaries you set together, to extend you love and desire, and to not actively try to undermine you or say insensitive critical, or judgemental things that damage your self esteem. Being around him should make you feel better not worse. However, you should not be putting the responsibility on him to form your self image or hounding and examining his every move to gather evidence of his desires. Right now, I do wonder how many of his cruel comments are unsolicited and how many come from you cross-examining him until he finally says the wrong thing? It is not a realistic position to expect your man to genuinely not find any other woman in the world attractive or to genuinely think that everything about your body is the best possible version of a female body that exists on the planet. Right now, it feels like unless he can genuinely convince you of this unrealistic idea, then you have found the evidence you need to feel worthless. That is creating a cycle of utter, utter despair for you.
I think it is important that you recognise your part in this desperate cycle and try to break it. Forget what he thinks of your body. What do YOU think of it? What can you love and appreciate about it? What simple ways can you be kinder or care for it? Can you book a massage for YOU, because it would give you pleasure? How can you explore or extend your self-pleasuring to know and enjoy your own body and desires more? Is there a step YOU want to take to work on an aspect of your body, or are you actually happy the way you are? Are you at peace with the fact that your priorities lie elsewhere right now (eg with a young child). This would be totally reasonable and is in your power to decide. Or would you be happier if you put some energy into changing something? Do you love and desire yourself, so ultimately, feel worthy of love and desire from others? (I hope so - because you definitely are!)
I think doing the work above will help you to deal with the man issue. If you do that work, and can look on your relationship with fresh eyes, with a sense of worth, things may become clearer. You will learn a lot from how he responds to your growing self love. Eg if you look in the mirror and say “I’m looking hot today” does he give you a hug and say “yes you are!” Or does he grunt or make a derogatory comment? You may start to hear his cruel comments in a different way… Right now his cruel comments make you think “I have proof now that he finds me unattractive”, whereas the new conclusion from these cruel comments might be “Wow- I’m currently with a cruel twat, and I deserve more- time to move on”.
Sending hugs.