I had no idea I had joined this forum and wrote this. Many elements of your story are intensely similar to mine. I hadn't been chatting online or involving anyone else in our relationship but was always emotionally unavailable and shielding myself through coping mechanisms. I definitely understand the shock of finally dealing with the havoc you have wrought after essentially being blind to it.. finally coming to grips with hurting someone you love is a terrible experience. I hate to say it but the damage is done. Just like my ex tells me, you cannot take it back or erase the past. However.. I think it is important to recognize she is alright (thankfully) at least in the capacity of being more healthy and seeking/found a relationship. You didn't permanently damage the person (or cause their cancer) - but I'm sure it was a very painful experience for her. Your path through therapy, and improving yourself, I would say is the right one. With that said, I think an important distinction is that you have to do it for yourself - you can't expect that she will change her mind or relate it to her at all. In almost any situation, you have to get yourself right before you can start changing things you can change in the world. Ultimately, once you are good then you can start building. I wouldn't look at it as a derailment so much as a very painful reminder of why you absolutely need to do this. Not many things are permanent in life. Peoples' emotions change, your situations change, everything is quite malleable. The bright side however is that you recognize you have an issue, what you need to do, and are seeking to do it - that is something a lot of folks cannot say. I'm beginning that phase right now as my second divorce is in process. I didn't take the time to get to know myself, take the time to really listen, and always thought I was okay when there were genuine issues that needed to be resolved within myself. I also worry about future relationships, repeating the same mistakes, but knowing is half the battle. One day at a time, set short goals to do one thing better each day, fix one thing, work on small steps. Small steps add up to big steps. I wish you the absolute best of luck and I know you will succeed in getting past this in a manner that works for you - just stick with it and really give it your all. Nothing (within reason of this analogy) is forever.