Hello, Thank you for asking your query at DoctorSpring.
I understand what you are going through. But, firstly I want you to understand that it's not a taboo to be fat, you are very lucky that your husband appreciates you. Its very understandable you are feeling low, but its time you pull up your self esteem. There are counseling sessions for this. Do not cut down on your food and nutrition, this wouldn't help you much. Instead reduce fatty food and have more of fruits and vegetables.
If exercise is not an option because you have hurt your knee, you can try doing yoga. There are specific exercises you can avoid which involves knee. You can also try doing meditation. You can pay attention on your diet, have more of protein like skinned out meat and egg, fruits, dry fruits like cashew and almonds.
Hope this helps. Please feel free to ask follow-up questions