I never have done. It can be very mean, imo, to straight out say something like “you - ex friend for example - trigger me”.... but I think it’s “ok” to tell someone if a particular topic is triggering to you. In fact, imo, it’s a good skill to have if you value your friends as this might come up at some point. It’s much “better” not to “leave it” sometimes ... if it’s a good friend they will probably understand. As you probably know, using “I” statements is much kinder and gentler than .. people who use “you” statements when talking about something difficult tend to be a red flag for me as most are intelligent enough to know this is sub optimal. But of course it does depend on the individual and the situation.

Oh I remember now, I did once tell a friend when she was saying something very triggering. She was ok with that and said she wouldn’t talk about it again. We stayed good friends. She has passed away now though (she was quite a bit older than me )

This post isn’t quite what I was wanting to say but hope it makes some sense. I don’t have time to edit it and don’t want to delete it.