I'm going through the same thing with my husband. I've lost 80 pounds too. He was insecure to begin with and me losing weight isn't helping. He is so scared that I am going to leave him for someone else. I've started caring more about my appearance which leads him to believe I am improving my appearance for someone else. When I go shopping for clothes, I try to include him. I ask for his opinion on outfits. I get things that he likes. On a daily basis, I tell him how much I love him and how sexy I think he is. All you can do is keep reassuring him that you love him and that you aren't going anywhere.