OP, you have posted with the question “are SAHMs lazy?” - even though this is obviously a non-question because it depends who you’re talking about. There are more / less lazy people in all walks of life.
However - your actual situation has nothing to do with being a SAHM. It has everything to do with the fact you are married to a financially abusive man. I’m sorry to say this and I wouldn’t say it often on here, but your self-esteem will never improve until you leave him.
As you say, even if you got a job, he would be quite happy to see you with less disposable income than him. Do you think this is in any way normal?
What is the actual point of this man? What is the use of him in your life? Sorry, but he is an absolute bastard and I’m raging in your behalf.
Just kick him to the kerb with his £600 a month. How dare he. Honestly, I would rather be in a hostel with my kids than pandering to that shit.
I’ve been SAH for many years and my DH wouldn’t dream of giving me an allowance like a child. This is because he is a normal human being and not a wanker.
I know a lot of SAHMs OP, probably a hundred or so, and who knows or cares if they’re lazy or not (how long is a piece of string) ? - but I can tell you this much ..., none if them have husbands who behave even remotely like yours.
Do you have anyone in real life you can talk to or who could help you to get out? He has obviously done a real number on you that your confidence is this low and you are asking bizarre questions about being lazy.
I hope you can get out of your toxic and abusing marriage. Your situation sound horrendous and I can’t believe that in the UK in 2020, there are men who think this is ok.