It's completely OK to feed everyone crap for a few days. And I doubt it's crap anyway. Fish fingers is very, very fine. Add broccoli and you've hit the five gold stars.
Your new baby is 7 weeks old.
You sound exhausted. You need support. In an ideal world, that support would come from your family, friends and partner. Sadly, they are probably all too busy. There is probably just a great big hole where that help should be, which means that you - the one needing the support - end up trying to fill it. And you can't.
The support that is supplied by outside agencies is not - or it shouldn't be - just for the seriously discombobulated: it's for people like you. you need to realise this is not just "middle class whining". The position you're in is that you need a bit of help and there's no-one around you to give it to you. That help can be as simple as someone popping round every so often just to chat and show that they remember you exist.
You also need sleep. Absence of sleep can drive anyone off balance.
A really good H.V. will see you regularly, and advise you to cook fish fingers. She'll cheer you up and keep an eye on you. It's no substitute for having actual help with the day to day work, but it will go some way to bolstering you.
You'll note that I haven't mentioned your relationship with your husband at all. I do wonder if he's a bit ... in denial ... about the increased level of work a new child brings. the darker truth might be that he knows, but doesn't want to do more himself. Maybe he already feels a bit close to the edge himself. Maybe he's a bit lazy. Maybe he doesn't know. Maybe he is genuinely a bit alarmed that you seem so cross a lot of the time. Maybe he's trying to shut you up.
I don't know any of the answers to these questions. Any, all, and more are possible. But I do think that if you grab any help going to look after yourself a bit, you will be getting towards a better place to anser these things yourself.
I don't think you're mad. I think it's hard, really hard, and society, not just your husband, has a vested interest in down-playing how hard it is. So all I can do is tell you that you are struggling, legitimately. It will get better, but many, many of us find the load quite hard.
(I moved while dealing with a little one and studying. It was horrendous, and it took a long, long time for me to get back to a steady place.)