Rose, you are white-knuckling. White-knuckling doesn't work, at least in the long run. You'll either break NC or do some other self-soothing behavior. Any self-soothing behavior in the long run is not good (even if it's going to the gym. Ask me how I know! My injury is finally healed, 2 years later).
Do you know the chocolate chip cookie/radish experiment? A group of people were tempted with chocolate chip cookies - the smell, the sight of them, etc. Then some people were given the cookies to eat and some people were given radishes. Then, seemingly unrelated, everyone was given a difficult task. The people who got the radishes made fewer attempts, gave up more quickly, didn't persist, etc. The conclusion was that there is a GENERAL reserve of willpower/self-control that is used across a variety of tasks and that it can be fatigued and depleted, at least in the short term. You are exhausting your self control every day and no good will come of it. Your work will suffer, friendships, health, etc. You need an off ramp.
I heard a podcast a while ago that helped me a lot - I'll see if I can find it for you. But here is a decent summary. I have no idea what research it is based on but it worked for me.
We (humans) have five primary emotions. When all is going as it should, we experience these emotions in waves. They enter our body, spike up, flow through, and leave our body. They are signals to us that are meant to be helpful in figuring out how to navigate the world. Love - this is a good thing for you, get more of it! Anger - something is unfair or unjust, it needs to be fixed! Primary emotions are supposed to be helpful.
Things go awry for a few reasons. The culture you are in might tell you one of these emotions is not OK (i.e. anger for women or sadness for men). Your FOO might screw one or more of them up (a mother might feel that she is not doing a good job when her child is sad and shut down their sadness). Or an individual might experience something in such an overwhelming way that they resolve never to go near it again. If you have an overwhelming experience with sadness you might retreat from anything that might be sad.
When primary emotions go awry the result is secondary emotions. We are NOT programmed to deal with these and they are NOT experienced in waves that then leave the body. They spin and spin around and become intolerable. Then you seek to soothe yourself from them.
You get out of this cycle when you re-learn to sit with the primary emotions as they wave through your body and leave (that's the off ramp). This is all that mindfulness stuff. Observing what is happening inside of you. I'm really sad. It's normal to be sad, I have experienced a huge loss. The sadness I feel right now will not be here forever And so on.
Secondary emotions: guilt, enthusiasm, depression, pride, vulnerability, regret, anxiety, contentment, disappointment, happiness, hope, jealousy, frustration, shame, confusion, lonely, trust, satisfaction, peace, resentment, confidence, optimism.
Primary emotions: Joy, anger, fear, love, sadness
You might find surprises when you go looking. I realized with a jolt that the emotion that was shut down in my FOO for me was love. Because if I shared that I loved something (like math or swimming) or if I showed loved to a person, instead of that being celebrated and more given to me, or the love returned, it was used as the thing that was taken away. My love of math was diminished because it made my little brother feel bad about his lack of achievement. I was taken off the swim team as a punishment for something trivial. So I stopped sharing what I loved and stopped even admitting that I needed or loved. When they relented and said I could go back on the team, I said no thanks, I'm good. What you took away - I never really cared about it. You can't possibly hurt me if I don't care about anything. The secondary emotions were pride, loneliness and confusion. (This also explains why I don't experience much guilt or shame, even after infidelity. I was used to saying nevermind, you don't matter much to me, you go your way and I'll go mine and we'll both be fine, even about my marriage).
This can also help you identify sources of STRENGTH that you can use. My family was great at helping me through fear (not in relationships but in sports, academics, moving independently through the world etc). Fear was not shut down or shamed but rather acknowledged and I was supported through it. As a result . . . I am not afraid of very much! (consciously experiencing and sharing love is the big one, but I'm working on that). Rose, I am super brave! And that has led to enthusiasm, hope, happiness, confidence and optimism. I can use all of those things to help with the stuff that I'm working on.
So. . . . you have an enormous amount of guilt and shame. You also have a fair amount of enthusiasm. Where did that come from? What else do you see in yourself? Can you stop spinning those secondary emotions?