Yes, I know it is much more likely that they don't get help and they just keep repeating the same cycles for most of their life. I just had so much hope and i truly love him so much. Or maybe it's a trauma bond because how can i love someone who has treated me this way? Did the things he's said. Done the things he's done. But it feels real. And so all encompassing. And I now that's part of the design but how do you even start to weed out what was real and what was a lie? I feel like if I didn't have much family or many friends, I would absolutely go back to him. I am now worried about disappointing them than I am about disappointing myself. Which I'm sure says more about me and my self worth than anything.

So sorry that you had this shock.  But he has a personality disorder.  That means he is mentally ill to some extent.  Not enough to be convicted and imprisoned, nor enough to perhaps be committed to a mental hospital.  But still... his perceptions are so skewed away from the feelings and realities of reasonably normal persons.

You no doubt tried to make it work for so many years but it's not that you failed.  BPD is a disorder most impacting to close relationships.  The very emotional closeness of the relationship seems to block the other from truly getting past the baggage of the relationship so that he could truly listen and take long term notice of your efforts.

You did try but it's time to Let Go.

First of all, don't beat yourself up over this.  He knew you would be there, right?  Let me say, therefore there's a chance he left the journal there knowing you would find it and read it.  When I was married, BPDxw loved to passive-aggressively leave little "trinkets" out for me to find, then get upset over my reaction, whether I read something, threw something away, didn't read something, etc.

Second of all, who writes that in a journal?  One keeps a journal to create a timeline and memorialize things for one's self.  What he wrote is basically a laundry list of everything he thinks would upset you.

I'm curious what the rest of his entries were like.  Did he just suddenly realize 12 years of marriage were bad and decided he needed to write that in case he forgot?

I completely agree, this is part of the sickness where you either focus on everything good or everything bad.  My ex did the exact same thing to me and at the time, I thought she was a complete monster.  But that's not really true or fair.  She thought those things in the moment when trying to feel good about herself...and that's what your husband is doing as well.  Instead of facing reality, he's creating his own version of events about you in order to keep any responsibility from falling on him. 

In other words, that's what children do.  Your husband thinks like a child.

As far as you reading the diary, at least you know for certain that the relationship is over.  While he hasn't been against you for 12 years like he said, it shows his current mindset and it would take years for that to reverse.  Again, I was in the exact same position and I was in shock when my ex suddenly flipped from white to black overnight.  How could it be true?  How could she think that way?  It's mental illness though and we're not supposed to truly understand it.

Just remember that his opinion of you is not what defines you.  He's sick and being childish.  And truthfully, he probably wanted you to find the diary because he's sick and childish.  Do not focus on this stuff because they're lies within his own mind.  When I went through it, the thoughts tore me up inside for months before I accepted the reality of what was really happening.