On many threads I’ve read posters tell the OP their partner/DH is an arsehole/ a dick/ wanker/ bastard etc and tell her to tell him this over their ‘wrong’ behaviour.
We have no idea what the dynamic is like here. It sounds like the OP’s husband doesn’t approve of/like her mother and is on hyper alert for the perceived negative traits showing themselves in her and their children.
Name calling is never a good thing, it’s rarely justified but it can usually be explained.
If OP is the type of person who is generally negative and disapproving of others and her husband is noticing her become more like her mother in this way it will naturally annoy and concern him, especially if he feels it will be adopted by their children.
You can dislike something but it’s the way you show and act upon it.
If OP found hairs or unidentifiable gross-looking objects in or on the cupcakes she would obv be justified in binning.
If she thought they weren’t sweet enough or the texture was a joke and proceeded to criticise the neighbour’s culinary skills, which led onto other criticisms like the state of their garden, the tacky decor, how much weight neighbour had put on etc, I can understand her DH getting fed up with her, especially if it’s a common monologue.
It seems rather extreme to bin simply bc she didn’t like them. Justifying this by saying the rest of her family don’t really eat cakes is dismissive and presumptuous and probably to vindicate her actions and her verdict that the quality isn’t up to standard. Did you offer any of them to any of them, OP?
If OP said to her son she’d accidentally dropped them/ the cat had licked them etc it would perhaps have been ‘nicer’ than - “They aren’t very nice so I chucked them” etc. It’s a lesson learned that kids innocently repeat things and if he was asked by another adult who he trusted and liked he’d have given them an honest answer. It’s really sad to think the neighbour would have probably got visibly upset/angry and the poor child wouldn’t have understood why and certainly wouldn’t have meant to say the wrong thing, bless him. He probably wouldn’t have thought his mum would have said something mean about them so it wouldn’t have occurred to tell a white lie. Very unfair he is being punished for essentially telling the truth!
Sounds like there’s a lot of growing up to be done all round, but mainly the adults.