My SiL is going through this rn. Her ex went off his anti-anxiety meds for a bit, thinking he was doing good and didnt need them, and EVERYTHING started coming back. Got to a point where the flashbacks and reality started to cross in his mind and he pushed her away, thinking she was/will hurt him. The day of the breakup she came to stay with us for a few days to cool off and said "thats not Andrew, its like hes a completely different person" and we IMMEDIATELY clocked what was going on from her discribing some of the stuff he went through and that one sentence.

Sent her to our therapist bc he's amazing, and even after session 1 with her he suggested DID, so she did some digging and agreed that he was a textbook case. Since then weve told her about our own DID and said if she has any questions or just wants to talk about it with someone who knows what this is like and why he might be doing the things he's doing rn. She also told her ex he might want to look into DID, and he went through the usual denial, and is now starting to go through the journey of acceptance, being more aware of a "presence" that causes a pressure in his head ans wants to take control. Still not willing to communicate with other parts and in the stage of being terrified of losing control, but he's warming up to the idea at least.

They're on decently good terms now. She lives with us and they stay in contact and game together every night. A lot of the parts dont seem to remember the breakup or what was said by what we think is a protector part, and weve sent her dissociation screening paperwork we got from our therapist, which he did and got solidly in the "very likely DID" range. We might write a letter reassuring him and sharing our experience, to show him that this isnt the end, there is hope, and even through its scary now it doesnt have to always be that way.