This is not of her business. Sorry to say but she needs to stay out of it. It is your life. It is your decision. She is not the one going through the pain. She is not struggling. It is easy to make up things. It is difficult to bear all the struggle. Tell your husband to convince her. Obviously, you cannot just hush her like that. I hope she gets on board. Show her some videos. Tell her that is legal. It is nothing to be ashamed upon. I hope she will think about it. Good luck with the MIL.