Nutrition facts formula for home cooked foods??

I love my MIL like she is my own Mother but, Im having a really hard time getting thru to her about processed foods. She was recently diagnosed with Sugar diabetes and high blood pressure. Since then she has been living off of frozen "diet meals", diet canned soups, as well as other so called diet snacks. She wont hear how bad they are for her at all! Even when I point out to her that one of her diet meals has over 800 mg of salt. She tells me that the carb amount is with in her limits and thats that. Lower carbs wont do anything for your heart when your BP goes thru the roof from all that salt!
I have tried to help her understand that whole grain and fresh veggies are a much better way to go. Smartly prepared home cooked meals not lab prepared meals will make you healthy. Ive even tried to cook healthy foods for her and she wont eat them. "Not that they taste bad (she says) but, I don't know how many carbs are in your food". OMG help!!!! Is there a formula that I and she can use to figure out the nutrition facts on home cooked foods?
After we had that discussion I think I have realized why she is eating so many frozen meals... If she cooks for herself there is no label on the pan to tell her what she is eating as far as carbs, sugar, salt etc...
Even thou Im so frustrated with her I could scream, I never show that to her! I want to help her so much but gosh, Im just not sure where to go from here.