SHOULD I CALL HIS MOM OUT??!

My boyfriends mother is constantly making snide and rude remarks about me, has refused to get to know me, yet passes judgement on me and manipulates my 20 year old boyfriend to do what she wants, and if he doesn’t and if the thing has to do with me, she threatens him. It is breaking my heart to watch how she picks him a part and uses his fathers death to guilt him. She has been incredibly disrespectful to me, through my bf. My mom and rest of my family say I need to email her and call her out and address her behavior towards me and him. By no means will I cuss her out, but rather be respectful yet assertive. WHAT DO YOU THINK????! Please help. She does the same thing to my bf’s brothers fiancé and the rest of her children.