but it's a healthy recipe

This morning I dragged my butt out of bed to come in to workout. I did an old bodyrock workout (12 minute magic) with two modifications, since the muscles around my tailbone I injured on boxing day still hurt when I do some things. Tuck jumps became box step ups and switch jump lunges became regular alternating step back lunges. Then I hopped on the elliptical for 30 minutes. I feel great! I missed this...

Last night I had an odd, frustrating conversation with my sister in law.  I was over for supper and we had a nice veg stew with toast. After we had some Japanese specialty cookies for dessert. Then my SIL (who now weighs over 350 Lb and is always struggling with her weight) brought out some Christmas chocolates. Then some homemade nut chocolate balls. I politely declined those last ones. I wasn't hungry and saw no need to mindlessly snack on chocolate, after having overdone it all holiday season. After this she asked why I refused - I said I wasn't interested. She said "but they're healthy - they have dark chocolate in them". She asked me if I'd help her make some other "healthy" treats next week. I offered to: turns out they are a mixture of 1 c each of cashews, almonds and puffed rice, with a spoon of chia seeds all coated in 300g 70% dark chocolate. Damn tasty yes, and while these would be OK for you, I wouldn't really call them "healthy". Especially if you eat them all at in one day. Which, unfortunately she likely will. I know that sounds harsh, and I don't say this to be mean-it's just true. I know this because she said so and offered to split the recipe with me so she'd only eat half. I am not really that interested in eating the other half...but I might take half, and then see if we can both try to freeze half of them for later maybe and both try to save them as a daily treat or something...
But then she said "and if you like that one, I have a healthy fudge recipe".
I just looked at her and said "It's fudge. How can you have healthy fudge?"
She replied "But it's a healthy recipe. From a dietitian's blog."
Again I replied "it's fudge"
"but it's healthy"
"it. is. fudge."
*quiet*
"fine...whatever. you don't have to make it" she muttered.
I tried to explain to her that the idea of healthy fudge is really a false idea. Fudge, even healthified is not a "healthy" snack. I refuse to be persuaded to say it is just to make her feel better about her poor food choices. (Plus, I admit I just don't like fudge much).

So I ask you guys - was I off base here?
It seems to me that if you have a sweet tooth and a weight problem you are trying to address, the last thing you need around your house is a pan full of fudge, "healthy" or otherwise. I admit I'm not big on sweets (altho I love me some peppermint dark chocolate) so the thought of a pan of fudge really makes my stomach churn to begin with. And I admit it made me angry. SIL is always commenting on how she is frustrated and jealous that I'm thinner and pushing me eat more whenever she wants a treat and "oh just have a bit more" and "drink fruit juice instead of water" when she does so she's not alone in doing it and it frustrates me. She's asked me in the past how to reduce calories in her diet and I've offered comments like cutting out some juices, and stopping the endless mindless nibbling on candy and chocolate and she says "but I like that stuff". Yet she is frustrated that she cannot seem to lose weight. She sleeps with a sleep apnea machine and can no longer walk a long distance or up lots of stairs anymore. Everytime she tries to exercise she stops because it hurts. Her health worries me. Yes they eat healthy meals but she snacks all the time on crap. She knows she needs to find healthier snacks. To me this would mean fruit, or a granola bar, or hummus and veg or something like that.
To her it means "healthy fudge".
Thing is...I made a new years resolution regarding my sister in law that I would no longer ignore or pander to her deluding herself with poor food choices. I won't offer opinions unless asked, and this fudge thing is just one example. I can't have "just a little of anything" and neither can she, so that isn't a valid suggestion. Any ideas about how to respond to something like this without being rude? Now that I'm done my thesis I'll be over there visiting a lot more and this will come up a lot. I don't want to be condemning or rude about food, because I've been there and hate that kind of thing. But I want to be honest with someone who isn't always ready to listen to the answers to the questions she asks.
Any thoughts??