I don't think ought to matter to your decision whether she still wants you or not. The trust is gone. You are recording her phone conversations. She refuses to give up the "friendship." It does not seem to me like she is ready to re-earn your trust, and you clearly do not trust her.

I don't know whether her feeling that you did not give her enough attention is only due to how busy you are, or whether it's because of a fundamental mismatch between you two: sometimes one person wants more independence and freedom in a relationship, while the other person wants a much more close-knitted life together. Whether you stay in this relationship or move on to another one, I would think about this very carefully. There is nothing wrong with either of these wants, but it is best if both people in the relationship match in terms of what they want. If it is such that your fiancee will always want more attention than you can or will give, I suspect that she will always be looking for something/someone else to give her what she wants. It is not the right thing to do, but honestly, I find it understandable.

I am sorry for both of you in this situation. It is very difficult. I hope you will figure out what is best for you, and do it.