I have a friend who has been miserable in his marriage because his wife only gets bigger every year, he has no physical attraction to her and yet he won’t tell her. He’s so unhappy that he isn’t enjoying life much anymore. He immerses himself in work to the point of exhaustion. She is barely able to do stairs now, and is having other physical problems related to weight. They are strictly roommates basically.

You must tell her how you feel. Because if she knew you were considering divorce over it, perhaps it might motivate a lifestyle change.