Hello! I read all the way through your post. I am going to be very straight forward and honest. Until your fiancee stops defending his mother, you are always going to be at fault. And yes, that is gaslighting. Your fiancee is not strong enough to stand up to her, to defend you, or to create strong boundaries with this most toxic relationship with his mother. If you choose to still marry him, this will always be a problem between you and you will always be at fault. Is that how you want to be treated in a marriage? In my opinion, your fiance is almost as bad as his mother. He should be defending you and protecting you and he isn't. If it were me, I would question whether I should marry this man or not. I would not want to marry him unless he can defend you, stand up to his mom, and separate himself and your lives from hers. She is very toxic and she is going to cause a lot of problems for you and for him. And he doesn't seem strong enough of a man to defend you. That is a big red flag in my honest opinion.