Hi misuniaziubek,
this is really good news. Taking a break, confronting his fears and to some degree yours was brave and it looks it paid off.

I want him to do DBT in time when he's ready, but the idea also scares me because I worry about extinction bursts and him taking his frustration out on me.
DBT and extinction bursts? DBT may result in some confused behavior at the beginning as the psycho-education and first insights take hold and the pwBPD experiments with new behavior and struggle with different new emotional situations.
Extinction burst are more related to boundaries and with the break you just did the first and one of the biggest steps to put boundaries in place. I strongly encourage you to follow that path and be consistent with them. The first ones are the hardest and you might have seen already the worst. It gets easier over time so preserve and extend what you already got.
Oops... My bad
Guess I'm a little underinformed.
I just worry pretty much about him learning new DBT skills then accusing me of not employing those skills and using it against me.
I still sometimes have these reflex reactions to him, or his outbursts, and then I have to remind myself, this relationship isn't like that anymore.
Like for example, I drove up Saturday to see him and he texted me 'heading out soon.'
I completely overreacted. Assumed that he had left without me because I was 10 minutes late. I texted him. "Wow, I JUST drove by your house a moment ago, you suck." Super upset, feelings abandoned, disappointed, the works.
He didn't really get it. He took it with a grain of salt, thought I was kidding. He wrote: Will be home within the hour.
Oh. He was leaving where he'd been working. Neither of us really overreact like that anymore. Our relationship is different. But I'd been triggered by the memory. I ended up kind of complaining that he wasn't here already, and that coming felt like a waste. He told me that I'd been too vague with the time when I'd be coming up, so he had given himself leeway, but felt very upset that I would ever call coming up to see him a waste. I instantly apologised for making that statement and explained that I was just feeling disappointment that I couldn't see him right away and felt like I'd wasted my own time by not being clear enough.
Misunderstanding over, back to our happy little paradise.
Sunday morning, he got angry with me when I told him that I need to use the toilet. Started ranting a bit. I told him, it's okay, I can wait. Apparently he'd been trying to fix the toilet from overflowing and was experiencing a lot frustration and was extremely tired. I left to go to his bedroom for a bit, feeling a little jolted emotionally, but repeatedly telling myself that it wasn't personal, he was simply angry with the situation and feared the extra pressure of my needs. Within minutes, he came into the bedroom all chip and happy and told me that the toilet was fine now and I could do my business. Kissed me on the forehead and told me that he'd been trying to fix it all morning and got really lonely and missed my company but felt bad about the idea of waking me up from sleep. I suggested he shower and then we could nap together for an hour or two. He loved the idea.
Things used to be so difficult and draining. Now we cooperate, I stopped invalidating him, learned to validate him, express my feelings rather than react, we both have really good boundaries in place, we talk through every insecurity as it comes up and sometimes he even validates my feelings when I tell him. I couldn't imagine ever having such a stable relationship with a borderline.
If only he would consider DBT. But perhaps in time.