My daughter Nichole was diagnosed with borderline at 15 or 16.
I'm not sure what you mean about a borderline episode per se, but there is a distinct pattern of behavior and a warped view of reality or way of thinking, perceiving the world around them and relationships with others.
For my daughter, it's a I love you, but I have to push you away before you can hurt me, because something is wrong with me so you can't possibly really love me view. And yes, looking at it that way it can cause some severe depression. Also anger issues and meltdowns. Lord knows we had all 3 to deal with for many years. But I'm not sure what you mean by an episode because Nichole would be fine one minute and be enraged the next with no reason that we could see. We had more issue with the "meltdown" part than the depressed part as it was more in your face and much more often......like oh maybe a zillion times a day on bad days. This child could flip a mood faster than I've ever seen anyone else do in my entire life, and I come from a family riddled with mental illness.
How I dealt with it? Treatment was not a choice, she went willingly or she'd be dragged there kicking and screaming. Medication, she'd take it willingly or I'd give it to her, and trust me she did NOT want me to give it to her. House rules with consistent consequences. And I did an awful lot of focusing on the child she'd been before the symptoms of Borderline (BPD) began to appear. The drama, I ignored as much as possible. It only leads to more drama. So as long as she was just ranting and raving, I ignored it. Destruction of property or something like that would be dealt with according to house rules.
I learned to remain calm in the face of the storm, at least on the outside, because she fed off whatever emotion she saw. When she'd rage (and trust me it often got ugly) it was like a 2 yr old who works themselves up into such a tantrum they don't know how to stop, so there were times I'd have to talk her down......and that meant fighting the circular logic and helping her to see that she was viewing things the wrong way. Sometimes I'd have to wait to do this until after the rage. She had a good therapist and psychiatrist who would also do this with her, which was wonderful in my opinion.
Finding the right medication combination to help keep her moods from constantly shifting helped a ton. But to me, the long talks we had where I and her docs helped her un skew her version of what was going on, is what helped her to get better. The whole I'm not worthy of being loved thing was the hardest thing to help her move past though.
The whole behaviors of I'm going to do these terrible things and say these horrid words to push you away thing.......is so you'll "prove" your love to them because they can't quite believe it no matter how hard they want to. It's not a conscious thought, but it's what they're actually doing. Nichole tried very hard to drive everyone she cared about away from her. It wasn't easy to watch the meltdowns ect. But during those moments I reminded myself that she did not really want to act like that, it was a warped coping mechanism.....and she did not even know why she did the things she did. So while she'd be raving, I'd just never for a moment think she meant a word of what she said. (which usually she didn't)
It was a rough and rocky several years. But now she's stable and doing wonderfully, off medications.
A really good book for you to read is Walking on Eggshells. Awesome book.
((hugs))