I think what you are describing is normal.
What I learned about shame is that it was there all along. It was created in my childhood and then I imagine it like a snowball going downhill that it collected more and more around it until it was a big ball of shame that was hard to unravel.
I think what GMC wrote is so very true. That when we are busy being stuck in how we feel about what we did then it is harder to show up for the BS. Shame creates defensiveness because it doesn't want to be acknowledged. It likes laying beneath the surface and poisoning us quietly.
Though at the same time, you aren't just describing shame, you are describing a higher level of self awareness. Before you didn't even see the shame. It created a lack of happiness, lack of self love, it created the need that became so big that you were willing to ruin your life over it. Now you see it. THAT in itself is a huge improvement, a huge step forward.
A great book I read is "The power of now" because it helps us to be more of a concious observer of our thoughts. It also explains about the stories we tell ourselves, how we hold ourselves back, and the effects of overthinking and overcomplicating.
Eventually, I think the goal is to be able to see ourselves objectively, while at the same time continuing to strive to be our best selves. Those two things grow and collide and become self compassion. When we have self compassion it allows us to accept ourselves, our past actions, and be encouraging with ourselves moving forward. This creates a space that allows us to have room for our spouses and their feelings. Because in essence what happens is we don't have such big emotional reactions because we have made our own peace. It takes away the feelings of wanting to be defensive, or want to run away.
Keep in mind I am still early in my own journey so I could be wrong. I just know that's what I have experienced. It's not perfect or there all the time, but as I have the next experience and the next one with my eyes open and being self aware it gets more and more consistent.
It's a process, and one you can't just say "okay I did it, I am done". It's more, the more things you process and put away, the more things you will be able to deal with, and the more things you will continue to grow and be able to deal with.
Remember when you are overwhelmed to practice self care. I find when I get overwhelmed or feel defeated, I start again with the basics of self care and then start climbing from there again. Your muscles to be able to do that will grow.
You deserve compassion, and you must learn to give it to yourself first. It would be an easier thing to get to if we hadn't destroyed someone else in our path of self destruction. It's not the easiest thing to get to compassion while you still sit next to that person and are trying to show up for their pain. It's a balance of remembering your goal is just to do better, and we can not erase what's been done.
It's really, really hard, IAT. I can see the growth and self reflection is there with you. The more open you stay to that the more you will grow into the person you want to be. At some point you will realize the hand-wringing and navel gazing was important in showing how sorry you are, but the biggest and best apology is doing better and being better, changing your behaviors. I try and focus on who I am trying to become rather than who I was in the period before, during, and immediately after my affair. Our BS needs to know we are sorry, but they also need to see they are not married to the same person they were at the time of the affair. And we need to be reliable. If we are not emotionally healed, we will seem less reliable until we are. It all just takes time, it's a process, and it's clear to me you are working on it.