Friend ,God bless you ,it takes a special person to care for a loved one/friend in that particular state of sickness.Just remember that she is not in her right mind and thus hurtful things may be said or done but that it is the illness and not the person talking.Keep showing love and care as much as possible. As the sickness progresses your friend may lose further touch with reality but always remember the good person and the good times you shared together,those memories can never be taken away.