united states - How do I talk about my abusive former advisor if people ask?

I was just at a conference where I met another grad student who - upon learning about my specialization and university affiliation - excitedly asked me if I knew Dr. -- and if he was my advisor (she's a fan). Deer in the headlights moment for me, as I did know Dr. --; he had been my advisor - one that until recently I admired and was very fond of. Only he's not my advisor anymore, because our once enviable mentor/mentee relationship is now in ruins. (In sum: he crossed a professional line with me, I called him out on it, he started punishing me for it in various ways, and it culminated in him stepping down from my committee and me reporting him to HR (human resources) when my dept chair dismissed my complaints about his abusive behavior. After effects: we're not speaking to each other, avoid each other as much as possible, I get panic attacks/have some sort of PTSD (Post-Traumatic Stress Disorder) whenever I have run-ins with him, and I've slowly become isolated from the rest of my department because he practically runs it and no student or faculty member wants/dares to step on his toes).

The thing is, I came to this university primarily to work with him...he and everyone in the dept knows this..and pretty much anyone in our field of research would assume that he and I are connected somehow, given that we're at the same university, and how much our research interests align. So, as I've discovered from this conference incident, I need to come up with a response for if/when people ask me if I know him/work with him/why am I not working with him. Personally, I'd love to just answer truthfully and throw him under the bus since that's what he's done to me several times over these last few months, but I know doing so will hurt me more than it'll hurt him. Any suggestions on how to handle those types of questions?

EDIT: First, thank you so much to everyone for taking the time to respond. I really appreciate everyone's feedback and different opinions. You've definitely given me a lot to think about. From reading the responses, I think I can clarify a few items if you think it'll alter your suggestions:

1. 
   

   "crossed a professional line" - admittedly, I intentionally used that vague term because it's very complicated, and also because he crossed that line in a few ways. One is of a sexual harassment nature, but I was reluctant to use that term because it happened in a very subtle and covert manner - so much that the Title IX (gender equality) office at my university said that technically his behavior (both initial line crossing and his reaction to me standing up to him) - however unprofessional it was - did not rise to the level of sexual harassment. But as I said, he was unprofessional towards me in other non-sexual ways as well. Ultimately, for the scope of my question, I don't think it matters much, because regardless of what he did to me initially, regardless of whether or not I had any right to be offended, and regardless of which specific incident he took issue with when I confronted him, nothing justifies how he subsequently treated me/how he handled his anger, which was essentially bullying me and then later gaslighting me and becoming verbally abusive/hostile when I tried to address the bullying.

   
   


2. 
   

   HR investigation: the investigation is ongoing; I filed my official complaint about a month ago, so hopefully I'll hear back soon re: next steps/resolution.

   
   
   


3. 
   

   I'm an American student in the U.S.

   
   


4. 
   

   The extent to which others know: a few of the the graduate students/TAs/my friends do know about everything that's happened. Some of the faculty do as well (including my other two committee members, one of whom is my new advisor; the other was also willing to take over as advisor) Outside my department: HR, Title IX office, the graduate ombudsperson, assistant dean of the college of arts & sciences, university police (Dr. - didn't do anything criminal...it was just a formality that HR had to observe when I filed my complaint) so his behavior has definitely been publicized a bit, but in a very hushed/behind closed doors sort of way.

   
   

Answer

I am very sorry to hear about your situation - that sounds very painful and I wish you the best in healing from it.

Personally, I'd love to just answer truthfully and throw him under the bus since that's what he's done to me several times over these last few months, but I know doing so will hurt me more than it'll hurt him.

Probably the biggest argument for answering truthfully isn't payback (no matter how richly deserved) but protecting your peers from the same experience you had. Against that, as you've identified, there is a risk of retaliation if he hears that you're doing this.

By reporting him you've already taken action to deal with this missing stair. This may discourage him from repeating the harassment and/or improve the outcome for the next student to report, if it comes to that.

I've been in a similar situation (not sexual harassment, but bullying and professional retaliation from an academic superior) and I understand that it's exhausting. Nobody here can tell you whether you ought to do more than you already have done.

With that said...

After effects: we're not speaking to each other, avoid each other as much as possible, I get panic attacks/have some sort of PTSD (Post-Traumatic Stress Disorder) whenever I have run-ins with him, and I've slowly become isolated from the rest of my department because he practically runs it and no student or faculty member wants/dares to step on his toes).

To be honest, it sounds as if this bridge is well and truly burned. You've formally reported him to his professional colleagues. This is a much more threatening step than informally warning off a potential student. At this point I expect the only thing restraining his behaviour is fear of professional consequences if he gets too blatant about it.

To be blunt, whatever you might have stood to lose in your relationship with him by warning off another student, you've already lost it.

What you do need to consider is the risk of giving him ammunition. If you make specific accusations against him, and he or colleagues find out about it, there's a chance that this could be used against you. You are probably best keeping it to things that are incontrovertible fact.

Other answers here have suggested deflecting the question. I'm not a fan of this; some people may notice the deflection and read between the lines, but not everybody catches that kind of subtlety.

You might consider something along the following lines:

"Yes, he was my advisor for a couple of years. I'm afraid we don't have a good relationship and I ended up making a formal complaint against him, so I'd prefer not to discuss the details."

You're not making any accusations there, so it'd be hard for him or anybody else to take this as an attempt at escalation. At the same time, it lets her know to keep her eyes open for trouble. In the event that she doesn't take the warning and he harasses her, it also lets her know that there is already a formal complaint on record against this guy, which may help then.