GR, I've read your previous thread after the 1st breakup.
Late January, after reflecting on all of my ex's BPD behaviours, I decided to break it off because I couldn't see this unhealthy relationship working long-term. At the time, I thought breaking up was a wise thing to do, that is, until I started missing him SEVERLY.
You thought it was wise to break up is your head speaking. Missing him is your heart. The fact your heart missed him doesn't mean your head was wrong.
You thought it was wise to break up is your healthy side ("what do I want for me" speaking. Missing him is the junkie coming off heroin.
We [edit] decided to start a "clean slate" and then agreed to communicate and "treat each other better" (his words) this time around.
"We decided". Not just you on your own but both of you...
I confronted my exBPD about it, made him aware of my conversation with the mutual friend and all the proof I'd been provided with. Not surprisingly, he obfuscated, denied it all, continued to lie about it, etc., etc. I reminded him how this broke my trust and confirmed many suspicions I had about him for weeks. He then sends a violently threatening text to the mutual friend telling him he "messed up something good" between him and me and that he's a malicious liar hellbent on breaking us up (taking NO resposnibility whatsoever).
Not to mention he betrayed the friendship with this guy accusing him of sexting in the first place.
My exBPD claimed how hurt he was over my accusations and how 1) he was just drunk at the time, 2) he was "lonely", 3) he was just "setting up" our friend to prove how bad of a person he is, and 4) the friend was just soo persuasive. Ugh. We concluded with me telling him to F*** off. He blocked me from Facebook and Whatsapp.
Your reasons for walking out were back up by proof. They were facts not accusations. So your ex was not hurt by your 'accusations' but by being confronted with what he did wrong. PwBPD don't want to confronted with things they have done wrong, it's a trigger for their primal fear.
Apart from that his excuses are just that: excuses.
Since then, he mysteriously unblocked me from Facebook (though we're no longer Facebook "friends". I sent him an email apologizing ONLY for my calling him nasty expletives during the dispute. Days later, he responded accepting my apologizies, but also acknowledging that he "knows his truth" and "knows who he is" and that he prays I'm well.
BPDs have a different way of processing words. Your apology for calling him nasty names has not been read like that. He most probably has read something like "I'm sorry for accusing you, you are so right, you never did anything wrong, you can trample on my soul to your heart's content, please take me back".
Folks, despite everything, despite knowing how capable of deceit and lying (and his past violence), I want soo bad for him to try to charm me back. I WANT HIM BACK, warts and all.
He has lied, still does, and will never stop doing so.
He has cheated, might well be with a replacement now, and will never stop cheating.
He has blamed you and others, still does, and will never stop blaming you and avoiding responsibility.
He has manipulated you, is manipulating you right now, and will never stop manipulating you.
He has betrayed you and will never stop doing that.
He has betrayed his friend and will always betray what ever friend for his own needs.
HE HAS HIT YOU. He will hit you in future. Most times domestic abuse becomes worse over time.
None of these points is a wart. Each one is a tumour the size of his head.
I'm struggling with the fact that I failed to communicate at certain times
Do you struggle with the fact that HE has failed to communicate and when he did, he lied to you?
and that I quite possibly abandoned him and the relationship too soon.
Seriously? When would have been the appropriate time to leave? When he has beat you into a pulp?
Several months ago, he always complained that I "give up too easy" and that always worried him.
Why have you taken this remark on board? Why does this get to you? Is it what you secretly think about yourself? He sure knows how to push your buttons... .
And what about what worried you?
He always assured me that he'd never give up on us. Never, ever, never, he would say.
So 'never giving up on us' means "I will never let you go. I will cheat on us, lie about us and to us, betray us by beating you, I will create the most toxic relationship I can, but I will never let you go". Never giving up is not a healthy thing to say, but if it is said at all it should be about fighting to make the relationship a healthy one.
My anger over the above caused me to hurt him with no benefit of real communication.
Anger is an appropriate respons to cheating. Why do you keep looking at just you having the responsibility for communication? Where was his communication? Other than the lying, the manipulation and the verbal abuse? A relationship is about 2 people, not 1.
I felt trust was lost and just raged and left.
You bet trust was lost! Trust was lost when he cheated, lied, triangulated, hit you, etc. THE TRUST WAS LONG GONE ALREADY...
I still love R. And, truthfully, I think we could've worked things out and had been in a better place.
Work out which things? Him lying, cheating, hitting? Those are not things to be worked out. Trying to spend more time together with your SO when you're busy and your SO feels neglected, that is something that can be worked out. Communicating better if both are adults with an emotional landscape to match is something to be worked out. Lying, cheating, hitting are

and they will not go away. Or are you saying by 'working things out' you are willing to accept that behaviour from him for the rest of your life? Are you making yourself that small?
I feel I did so much wrong and have made mistake after mistake after mistake in light of his BPD (in which I've learned loads about since falling in love with him).
Guess what? People make mistakes. All of us here have made mistakes. I know I have not always responded in the best way to my ex now I realize be probably has BPD/NPD. But I also know it wouldn't have mattered. Because if I hadn't made the mistakes I did I would have made different ones. Another look or word would have triggered him. My biggest mistake was entering the relationship in the first place.
Yes, I want him to reel me back in. And I know I'm going to accept.
So that is how you see your life? That is how much you think you are worth? Being with a guy that will always cheat on you, lie to you, triangulate you, create drama and will beat you? Knowing it will get progressively worse? Do you want to end up in hospital? Do you want to feel and be unsafe forever? Run the risk of an std? Do you want to be isolated from your friends and family? End up all alone with an abuser and a tyrant? Do you honestly think that the occasional high after another cycle of idealization-devaluation is enough 'happiness' to weigh up to ALL of the unhappiness this guy and this relationship will bring you?
Pathetic, and I'm losing my mind.
You're not losing your mind, you're addicted. You want your fix and you don't want to think about the consequences. Even if you end up dead because of it.
GET HELP.
You need to get away from wanting your fix. You need to get away from him. You need to learn why you think so little of yourself that you are willing to accept all this cr*p.
GET HELP