Because of lots of things (diet culture, society being bigger in general than we probably should be, perceptions about couples 'matching' visually), people are weird about weight loss.
Being thinner (and losing weight) is seen as good. Therefore, people who aren't thinner or aren't losing weight can sometimes internalise other people's bodies and what they're doing as an implied judgement about themselves: Sarah's lost weight so she must be 'better' than me, I'll make a comment about it to make a point.
We're really obsessed with weight culturally, look at the front of any women's magazine.
So your husband might feel that you're leaving him behind, or 'getting too good for him', or are judging him because he hasn't lost weight, or he might be angry at himself for not doing the same, or he might be feeling insecure in comparison. It's not really a reflection of you (I assume - you're technically a healthy weight, so unless you're leaving out the part where you exercise 3 hours a day or have disordered eating, this is more to do with what he thinks how you look means about how he looks). Hence his defensiveness when you suggest eating less to him - he isn't happy with how he looks and he knows that that, in societal terms, means he is 'less disciplined', 'less attractive', 'less good' (thank you, diet culture, for fucking up our relationship with a healthy weight). By comparison, you have lost weight and look 'better' or more 'disciplined' or more 'attractive' - and he doesn't like that by comparison, you are therefore 'winning'.
Same with your friend. Women especially have these conversations all the time - we prize weight loss highly. A friend of mine lost 6 stone (which she would admit she needed to lose, granted) and people asked her how she did it all the time, pointed questions about her getting smaller and smaller, people praising her - she eventually had to tell them it was because she had developed a chronic illness. And the response was very often "oh that's terrible, well at least you're getting a benefit from it!".
So like I said, unless you haven't said the full truth and you're continuing to lose weight in an unsustainable or concerning way, people are just... weirdly obsessed with how other peoples' bodies look and what they assume that means about their own relationship with their body. It's not really about you and it can be very wearing - I'm not sure how you shut them up, but you're not being oversensitive.
All of this is so tied up in our weird culture of ascribing moral value to how someone looks or what they weigh as well as the explosion of types of food we just didn't have 50 years ago, adding layers of issues on how people view food, and causes really shit, below-radar-but-still-disordered relationships with food that explain both obesity and restrictive eating disorders It's tiring bullshit.