Can anyone help me strike a balance here? I know a lot of folks in this forum have seen their fair share of PDs and bullies.

I’ve been getting bullied by a coworker I'll call Tammy. We're equals. If anything I probably make a lot more than her. Our boss has told me in so many words that Tammy’s employed as a favor at this point, she's unreliable because she has a lot of mental health problems. She says she has bipolar and borderline. Every year she’ll spend a month in a hospital claiming she’s suicidal. She doesn't get along with coworkers and has scared off multiple clients by being inappropriate or rude to them.

We’ve been at the same company for several years and we never spoke. Tammy hardly even looked at me. Then out of the blue she started emailing me all the time, saying passive aggressive things about my work. Ultimately nothing she thinks matters. I’ve kept our boss in the loop about it and he’s “on my side” so to speak. He’ll speak to her, she’ll leave me alone again, and then about 3 months later this dance will start all over again. We don’t do any work together so there is literally no reason for her to contact me. She rifles through my work looking for something to knit pick or complain about. It’s obviously bs.

Usually I don’t respond to her emails. Just read and ignore. Sometimes I even take the criticism and make a change. But other times she’s downright rude and I feel compelled to email her back and assert my boundaries. I was abused by an NPD dad, and HPD and APD were also represented in my family. I’ve had so much therapy just to learn how to set and enforce boundaries. Putting it into action is very hard for me but ultimately it's comforting. I spent so many years beating myself up and not defending myself that I've seen my fair share of depression and self-harm too.

I understand BPD and it’s a no-win situation. She perceives a slight, attacks me and if I defend, she'll take that as a slight as well. She literally told our boss that “we hate each others guts.” I don’t know where that’s coming from! I hardly know her, I don’t hate her and I haven’t given her a reason to hate me.

Am I right in responding to her or should I just ignore her ALWAYS? I want to be assertive and stand up for myself because it's comforting. But I also don’t want to feed the beast. If a borderline thinks you’re a great outlet for misery and strife, will they ever leave you be? What does a trauma survivor do in this scenario?