Ok, so, you have no interest or desire in having sex with your fiancé, you disapprove of his looking at porn (and actually consider it cheating), he says you aren’t meeting his needs, and you’re wondering if the issues you’re having are your fault? Yes, yes, they are. As a romantic partner to someone, you have certain responsibilities, including getting yourself healthy and emotionally stable so that you can satisfy basic physical and emotional needs within your relationship. Not only do you not seem to be doing that, but you are actually blaming your fiancé for your own insecurity. Because you feel insecure about being overweight and because you have flashbacks of past experiences, you consider it “cheating” when your boyfriend looks at porn. Looking at porn isn’t cheating. Just because you say it is, doesn’t make it so.
Rather than make your boyfriend pay for the issues you have, you need to be proactive in seeking help and treatment. If your anxiety, depression, bipolar disorder, lack of libido, and low self-worth (not to mention your unresolved issues around whatever experience you keep flashing back to) is keeping you from having an emotionally healthy relationship (and life, in general), it is YOUR responsibility to get help. In the meantime, you should put your relationship on hold. You can’t focus on someone else’s needs when you have so many unmet needs of your own that you have to take care of first.
You’re not ready to be someone’s girlfriend, let alone someone’s wife. And, as your fiancé already said: The restrictions you’ve placed on him within the limitations of your own ability to love him are a deal-breaker. So it sounds like the decision to MOA has already been made for you anyway. I really hope you use this time to focus on yourself and get healthy. It’s not your fault you have the issues you do . . . but it is your fault if you decide to sweep them under the rug and continue letting them ruin any potential you have for happiness.
If you have a relationship/dating question I can help answer, you can send me your letters at firstname.lastname@example.org.