It's normal to feel guilty for going NC. I suspect you are feeling rejected again, that old record that toxic parents are so good at playing.
I went NC with mine. I did send one last email as a 'last' word and then that was it. They even went further to block me from everything, emails, facebook, etc. So even though I closed the door on them, they made sure to slam it a few times just to make sure I knew who was boss rolls eyes.
You can't control how they feel about you. The whole point of going NC is to protect yourself from being hurt again and again. Now the trick is to stop hurting yourself by doubting yourself for doing it, or even worse, to still yearn for that attention from them, even if it is negative.
Now this is all well and good to say this, but mind you, I went NC in real life one day and it then took me a few years to really feel like I made the right decision. You know why? Because it was only with not having them in my life that I could see how miserable they made me feel. And each day, each month and each year, I felt better and better and I knew then, their poison was diminishing.
Mind you, I am still messed up from them and continue to go to counselling in the hope of having 'normal' relationships with people, so the damage has been done for life, but hopefully I can find ways to work around it.
You did whats best for you for a change. Stick with it. Write that letter to them and then burn it and say goodbye.
