Can you remind me if you have a lawyer?
And have you started doing some online research for your province and situation? (i.e., looking for province-specific forums/boards)? You may have already seen
Canada Legal Help which does allow you to sort by province for resources.
Sometimes down here in the USA, the suggestion can be that if there isn't an official diagnosis (with documentation from professionals), then trying to "prove" to the courts that "she really probably has BPD" is a losing track. Focus instead on the crossover between her behaviors and the law.
For example, you likely have no documentation of her having any diagnosis, so don't try to suggest she has a certain MH issue. Instead, you likely have (for example) cell phone records, text records, third party witnesses, etc. Is her name on any rental or lease documentation (home, vehicle, etc)? Did you ever share a bank account? Maybe focus on putting that information into a robust and detailed timetable:
"On Day/Date, she texted me 67 times between 1pm and 2pm (timestamped records attached). 34 of those texts called me a name and 6 of the texts made a threat. On Next Day/Date at Time, I responded with 3 texts saying XYZ (attached). Immediately following that, she sent 44 texts (timestamped records attached), 20 of which made legal threats and 2 of which made threats of violence."
She was trying to take a
sliver of a snapshot of context (your responses after her behavior) and used that to get you. Put together a
whole timeline with dates, facts, witnesses, texts, call records, etc, and that may show her behavior and the issues more than any label.
Of course, if you have a L, run all this by your L first!