You may find that the tenant has a mental illness of some kind and it can be difficult for him/her to control the behaviour. If that’s the case, I would almost bet that the Tribunal would give him/her a “second chance” and you’ll be waiting forever for this to finally be resolved in a way you can live with.
Have you spoken directly to the landlord? Getting the landlord involved may be the cheapest way out of this (via eviction at the appropriate time and for an appropriate reason that can’t be challenged – could the unit possibly need renovating? Or does the Landlord have a family member who’d like to move in for a period?)
I also suggest maintaining a detailed log of incidents – time, date, nature of verbal abuse, background to incident, Police involvement.