Hello, I'd like to help you with your question.
You are not wrong for how you feel. You may have done things in the beginning of the relationship to cause mistrust, but you have taken action to fix those things and to prove that you can be trusted. However, your fiance seems to have his own issues with trust. It sounds like he is using what you did to try to control you and prevent himself from getting hurt again.
When two people enter into a relationship, they bring all their past issues with them. Many times, if they are not aware of them (like you are of your own), they put those beliefs and dysfunction on their partner. And the partner then becomes unhappy because they spend their time reacting to the issues rather than developing the relationship. It sounds like that is what your fiance is doing. He hasn't worked out his own issues so he is putting them on you, trying to make you do things that lessen his anxiety
about trust. However, it is not working because he is not feeling better and you are miserable in the relationship.
Your fiance needs to accept that you have done what you can to repair the damage from your past and now it is up to him to deal with his issues. No matter how long he tries to control you, he is never going to be able to trust because the issue is no longer you, it's him.
Your fiance needs to be willing to face his past and how that has affected his believes about relationships. He was abandoned so he probably fears you leaving him the most. But trying to control you is not going to make you stay, it will make you leave, exactly what he doesn't want. So getting help for his issues is imperative. Without help, he may stay on the same path as he is now, destroying your relationship.
Learning more about trust is good. However, your fiance needs to be willing to see himself as the issue here, not you. Talk to him and let him know that you support him but that his demands of you is hurting the relationship. Encourage him to see a therapist. If he won't go to a therapist, try asking trusted friends and family to encourage him. You can even see if he will talk to his doctor. Some people will listen to their doctor when they won't listen to loved ones. Call the doctor ahead of time and let him/her know what you are seeing. It will help.
If your fiance refuses to do anything, then it leaves you to decide if you can continue in a relationship like this. He is bordering on emotionally abusive and likely will not get better without insight and a willingness to get help. You may want to consider therapy on you own then, to decide how best to handle the relationship.
I hope this has helped you,