Verbal abuse may be common if this person is in an extreme manic state or approaching a manic episode.
First thing,you cannot argue with them,cause it won't work,it only stirs the agitative state,risking ending in violence.
I grew up learning this,back in the 60's when my oldest brother had his first breakdown,things were horrible.
In the 70's he was put on Lithium,the only drug that was a success,and it still is an excellent med for this disorder,has the longest track record and is non sedating.
In the sense,I mean the person can still function,work,drive,etc. while on this med.
Is this person you are mentioning taking meds and seeing a pdoc on a regular basis? That is so very important,as well as staying in contact with the pdoc when things are worsening.
Keeping the pdoc abreast of episodic behaviour can help in the way of med dosage adjustment and/or change being made.
The amount a person will put up with living or not living under the same roof, varies, my parents tolerated a lot,but then it was their kid, not the same relationship as a spouse or friend.
Another thing I learned, is certain things the person may say,one has to take with a grain of sand sometimes or just tell yourself the person doesn't mean everything they say while they are going through an episode.
The person has to personally judge what they can or want to tolerate.
Naturally if things are taking form of violence,that person may want to call the authorites,but be sure to state the person is having a manic episode and needs to be hospitalized.
This is the best I can think of from what I have seen in my life,growing up in a household with this.
Fortunately,since the 70's,my brother is still on Lithium,and has managed a good life,is on his 3rd marriage and it looks like for keeps.
Stabilization takes a lot of patience,work and time,for the patient and the non-bipolar.
Proper diagnosis is important too,in order for the person to be on the right type of meds. a person can more than one disorder,the most obvious one is best addressed ASAP.
Example: a person can be Bipolar and also have ADD,pdoc's will treat the Bipolar first and then later on possibly the ADD,in that order cause most treatments for ADD are stimulants (there are non stimulants too)which can fuel agitation.
Once true stabilization of the Bipolar has been accomplished,then it can be determined if the behaviour(s) where strictly of Bipolar nature,and not just ADD or both disorders, being that both disorders can overlap or symptoms can be similar,but need to be treated seperately for obvious reasons.
I hope this was of some help to you,for I share real life experiences and know I'm not an expert.
Sometimes RL experience can be more exact than "book learned" experience.
Hope all goes well for this person and the person with Bipolar disorder.
Take care now,
DE