answer:You are in control here, and get to stand up for yourself. You get to be the one that demands acceptance from them, or they will not have the pleasure of your company. Yes, it is not easy, and there are lots of cultural issues at play here, but you are grown and have a partner. You do what you need to be happy. Don’t offer to stay away to make someone else comfortable; show up, stand up for yourself and your partner, and if they get uncomfortable, they can leave. You have a right to be at your mom’s. Don’t let a bigot’s prejudice be more important than your right. If the brother in law gets between you and your mom, who do you think your mom will choose? You! You are her son. Write your sister, and tell her you will not be restricted by her fears of her husband. And she doesn’t have to be the one to tell him, but let her know you will not back down at the next family event. And if she does not accept you, then she will lose the privilege of you in her life. Be conscious of your not wanting to be in the life of someone who does not accept. Not accepting you would mean she didn’t love you.