After reading this thread, and your last one, I sensed that I had read similar posts from you before, so I went back and skimmed through quite a few of the threads you have started over the past couple years to get a clearer picture of your situation.
There were definitely some patterns and themes that I noticed that might explain why you've been spinning your wheels, staying stuck and why your BS is growing increasingly frustrated with you.
One of the biggest issues I see, and one that explains the disconnect that truthsetmefree touched on, is that your motivation to change is extrinsic rather than intrinsic. As you have stated, the only reason you have done IC, been on SI, or read books is because your BS has pushed you to do those things, not because you have a deep drive and desire to do them for yourself. There is a superficiality to the things you've done so far - a lack of depth - because you are doing things out of fear of losing your BS, rather than truly wanting to grow and transform yourself.
Which brings me to my next observation, the half-assing it and complacency that has been your self-admitted pattern, and that your BS has repeatedly pointed out to you. You're heart isn't in it. You are doing things with an expectation of a reward - validation from your BS and her continuing in a relationship with you.
In one of your previous threads you stated that you 'keep trying to "prove" to her that you are trying to change' and when she tells you she thinks that you haven't you get 'upset and defensive'. If you are truly motivated intrinsically to change you don't look to prove to others that you are transforming yourself, you learn to validate yourself.
When your BS threatened to kick you out in August 2016 she pointed out this pattern of complacency to you and you came on here asking for advice on how to stay motivated. At that point you even admitted that you give up if you don't get immediate rewards for your behaviour. You make half-hearted efforts to change and then when you aren't getting external validation for the things you've done you get upset, defensive and complacent, until your BS withdraws or threatens to end your relationship then you panic and once again start trying to prove to her that you are changing with more half-hearted efforts. Lather, rinse, repeat.
Until you develop intrinsic motivation to change and grow, or your BS finally has had enough and leaves, this cycle will continue to play out over and over.
Another observation I had and what I think keeps you from having that deep inner drive to heal and grow for yourself, and keeps you stuck, is your profound shame and self-loathing.
In March and August of 2015 you said that you "don't want to stop the self-hatred" and that you "will always be a piece of shit". You cling on to that shame and wrap it tight around yourself. You CHOOSE to maintain it. The thing with doing that is that it leads to self-pity, and as ISSF pointed out, it keeps you in the role of a helpless victim.
When shame and self-loathing are at play it disrupts your ability to empathically connect with others, and leads you to turn inward and away, which impedes remorse. Your BS sees that lack of empathy and genuine remorse. In July 2016 you posted about your BS saying that you are "cold" and that you "lack empathy" and then in December 2016 you posted about her saying that you are "defensive" and that you don't validate her feelings and pain. She has told you what she needs, yet you can't give it to her because of your need to hold on to the shame and self-loathing.
Having the motivation and desire to make lasting changes and psychologically transform yourself comes from a place of guilt instead of a place of shame. Shame says "I am bad", whereas guilt says "I did bad", and it is guilt that keeps us striving to improve.
Making the shift from shame to guilt involves developing self-compassion. I'm sure you've read that in the Brene Brown book that you've been reading, and if you haven't read it already I highly recommend you pick up a copy of Kristin Neff's book Self-Compassion. I also recommend that you watch videos by Brene Brown, Kristin Neff, and Pema Chodron on YouTube. I have some mod-approved links to the ones that BetterFuture13 and I found most helpful in my profile.
Once you develop compassion for yourself you can let go of the shame and self-loathing which will then allow you to really connect with your BS's pain on a deep level and feel true empathy for the hurt you have caused her without taking it as an attack and trying to defend and explain yourself. It will help you to stay present with your BS's suffering and really hear her pain and validate it in an empathic way. It will also help you to be more proactive about helping her with triggers, instead of ignoring them like you've done in the past.
Another area that needs mentioning, I think, is your Borderline Personality Disorder diagnosis from September 2016. I responded to your thread back then relating my own experiences with having BPD and recommended a book and video for you. I'm not sure if you ever looked into them. You did say you were supposed to start treatment at the end of September 2016 but never posted about it again. Did you ever get on meds? Have you been in DBT skills classes? What have you done to help yourself with your diagnosis?
I bring that up because it certainly contributes to how you view yourself and others, and how you behave and interact. Part of developing that intrinsic motivation to change is going to come from learning to manage your BPD and its symptoms.
Developing mindfulness is key. It will help you to be less impulsive with your words and actions, develop the ability to regulate your emotions, deal with feelings of shame and self-loathing as they arise in situations and in general. It will give you the ability to consider other perspectives. The book Mindfulness for Borderline Personality Disorder by Blaise Aguirre and Gillian Galen has been a game changer for me and I highly recommend it for you.
When you learn to be mindful, develop self-compassion, and find the motivation to change from deep within yourself rather than for anyone else, you will be able to transform yourself while simultaneously giving your BS the things she needs and wants - empathy, validation of her pain (that you deeply understand it), as well as feeling like she has been heard and that her feelings are a priority for you.
You have a choice to make - you can continue to spiral downward, repeating the same behaviours over and over and never really growing, or you can find the motivation within yourself to transform your life. You may not be able to save your marriage, but you can make yourself psychologically healthier and be a positive influence in your children's lives.
The choice is yours.