Utter Despair - New To Community

I'm writing out of utter shame and despair. I, like us all, have a long story so I'll try my best to keep it brief. It's also hastily written.

I'm 30ish, living with ADHD(on Meds, Adderall), Learning Disability, panic disorder and PTSD from childhood sexual abuse.

I am engaged to a beautiful, brilliant, generous woman who accepts and loves me despite my many shortcomings. She even moved half-way across the country to be with me as I started a doctoral program. I realize now, perhaps too late that I have not been as kind to her as she's deserved. I have struggled to do what I said I was going to do so many times in so many ways, financial, emotional, and more. It's undermined her basic trust in me. And often when she raised this with me I would become defensive and blame her for her "unrealistic" standards. In short I blamed her for the very kind of insensitivity I callously dumped upon her. While there were some instances in that I still think I was "right" I now look back and realize that my denial about the severity of my condition and defensiveness have made her life miserable over the past few years.

To top that off I have been blatantly dishonest with her. I have been struggling with a pornography compulsion that led to me to looking at escort advertisements and even making a few phone calls but NEVER CROSSING THE LINE TO INFIDELITY. She confronted me about it over a year ago and I responded with defensiveness and meanness for a while before breaking down and being completely honest with her. Over the last year my stress level has risen as the demands of my doctoral program shredded my confidence and exacerbated my anxiety disorder. I relapsed with pornography and escort materials and we drifted farther and farther apart as I continued to protest that everything was fine. A few weeks ago my finance confronted me about the escort website history she found on her computer. I admitted it was mine and we had a very difficult conversation. Two days ago she looked over our phone records and discovered that I had been blatantly dishonest with her again. I'd gone out of contact for many hours the night before her birthday and given her an elaborate story about it and berated her for not believing me. When she confronted me about this I told her the truth but she has lost trust in me almost completely. I've been so dishonest in so many little and big ways and hurt her so much that she says she can't get past it. I understand and feel miserable about how I have treated her. 

I am now in intensive therapy for my trauma, starting medication for anxiety, and have taken a medical leave from school. For the first time in my life I feel like I'm in the position to make some very large life changes. But it might be too little too late. Our time together has been filled with good and love as well as all the difficulty I've listed. We are in love but I don't know what to do when I know I've hurt her and don't want her to be in any more pain at the same time I'm confident that we can get past these challenges.  

How do we rebuild the trust?

Am I right to hope we can heal and repair our relationship?

Please be kind in your responses, I am fragile. 

Thank you.