I really hope everything is going well for you. I am doing NC for 4 months now and I start doing it since the first day my ex told me when I called him after he totally disappeared for several weeks. And he just said to me "I can't love you, I have tried already but I really can't...blah blah blah". Those words hit me hard like hell. I felt like I gave him all my heart, be his supports, treated him really nice, and cared deeply for him, and those cruel words are all I got. He didn't even try to make it nice. To be honest, I really have to admit that the relationship was not that good or healthy and I should step out of it earlier before having to listen to the above. Anyway, I learned now.
When the relationship was not working for whatever reasons, over-analyse it only drives you crazy. You may have so many questions like "Is it my fault or her?" "Why she doing this to me?" "Was it because of my insecure?" "What's she thinking?" "Did she realize she make a mistake?" "Should I contact her?"
Over thinking about all the above are putting you in the dark tunnel and can't see the way out. What I did is that I go NC very strictly in order to distance myself from him and total get him out of my life. I try to use my head and think rational about the situation. I learn to accept the reality that whether it's my fault or his fault, it's really doesn't matter. Do I want him back? (No!) Can I trust him again? (No!). This is not working, we are not compatible, and I will move on. I believe that I deserve better and I know better and learn from my mistake now. I will not make the same mistake and learn to love wisely in my next relationship.
YOU HAVE TO ACCEPT THE REALITY AND FACTS, THEN MAKE A DECISION, AND ACTED UPON IT.
It's not easy at all, I know. I don't have that much problem with going total NC with my ex. I never really want to contact him at all anyway. But I still have some problems of over-thinking and dwell on the past sometimes. I have to tell myself that I made a decision already, so I should just stick to it by leaving the past and the pain and all those questions I never get the answers behind, then start to rebuild a life I enjoy on my own and be happy again.
I wish you the very best.