We have a health care aide working for us monitoring my 97 yr old alzheimered father?

shes columbian,and has a thick accent,i often find it hard to communicate with her and find myself getting involved in deep rooted arguments,shes been with us when my mom was alive mom had many ailments and this aide was hired to ist both my parents,now,on my moms deathbed she made the aide swear that shed take care of my father of which she agreed.there have been a few scs that the aide has started,and doesnt think she did,but shifted the fray over to me,in other words it was all my fault.now shes threatening to quit,my brother whos power of attorny,hired this aide 4 years ago,hes said if you ever give the aide a reason to quit your *** is gr and im the lawn mower! the last time i got in trouble he took my laptop away for 4 months,now if he fibnds out the aide isnt happy here ill be in deep **** again!! i mean,this aide is an expirenced troublemaker,shes an expert in causing trouble.if i do something i cannot say im sorry she gets louder and louder and will not let me speak.i cant win----or can i?