My therapist is absolutely lovely, so I think right off the bat I've had a better experience than others. I once said that my reaction was "beyond stupid" and she made sure I never called myself or my reactions "stupid" again. She's taught me how to validate my feelings and to refuse to put myself down for them. She says to me that if anyone had the experiences that I've had, that they would only do the same and that it is difficult to re-pave these paths.
The tools I've been given through solo DBT therapy has been key in my progress. There are outside factors of course that made my symptoms worse that are no longer present, but the core of my relief has been what she's taught me. Small things, like for instance, when my anxiety is skyrocketing I'll now rub my feet on the floor and describe the sensation, or internally verbalize my every action. This helps me to stay grounded in the present. Or, when I'm feeling overwhelmed and ready to explode from anger, I'll say, "I can't change what's happened up to this point. It's already happening. Now what can I do?" It seems so little, but realizing you can't control every action leading up to things helps me cool down and tackle what I can accomplish or change.
There are some other things I've learned so far, but these have been the most helpful for me.
Side Note: My symptoms have not disappeared and I am not void of BPD symptoms still. However, it has dramatically lessened my outbursts and for me, that's a HUGE win. I was on the brink of losing my job and my boyfriend, which would have absolutely wrecked me.