!!!TW: briefest mentions of abuse, sexual assault, suicide (no details or descriptions provided)

One of my closest friends has PTSD, and so do I. We both have had pretty similar trauma experiences, similar abuse, etc. But something I’ve noticed is that this friend seems to have a tendency to overshare, and isn’t really the best with boundaries. She seems to be aware of this tbh, and even makes jokes about her boundary-stomping tendencies. For instance, she’ll occasionally casually mention explicit details of abuse, sexual assault, or even suicide etc. in our group chat, without warning. Or make explicit trauma jokes that end up being rather triggering or concerning. This is very jarring for me, and usually triggers my ptsd or a dissociative response for me.

I like and care about this friend a lot, but it’s difficult for me to hear her casually mention explicit traumatic details with no prior warning. I do have a tendency to share too little info about myself, and be a bit on the secretive side, so that could be a piece of my discomfort. Because of my freeze/ fawn response, I’ve really been having trouble setting boundaries with her when she does this (over text AND in person). (She primarily seems to do this over text, though.)

I don’t want this friend to feel like she can’t disclose anything to me anymore, or like I don’t want to support her. But I don’t think it would be healthy for me to keep getting triggered by her out of nowhere due to a lack of boundaries in this regard. At the same time, as someone with a similar abuse history, I feel obligated to support her and to listen to her, because I don’t think anyone else will. But then again, she also has therapists for that purpose, right?

I’m used to having super unhealthy, codependent abusive relationships where people would basically treat me like their therapist, with no regard for my wellbeing. I’m worried about this friendship escalating into another one of those abusive friendships I have had in the past. Sometimes this friend reminds me of my past abuser.

Can anyone advise me on ways to set boundaries in this scenario? Is this behavior a red flag in her part? Admittedly, this person is one of my best friends, and the number of friends I have are very few, so I wouldn’t want to sever the friendship altogether, if it can be avoided. It’s also extra difficult for me to stop her in the moment since I tend to just dissociate and go kind of numb when it happens.