How do I stand up for myself when we row?

[PlayOnWurtz]

I always freeze and can never say what I want to say, he always goes off on one at me and I'm left feeling like I've been told off like some naughty child.

This is not me. I'm normally the gobby person quick with a response quick to stand up for people and really assertive but with my husband for whatever reason I can't stand my ground and just sit there and take it.

That doesn't sound like a "fair" fight Play. Are things okay with the two of you in general?

Not really all that great. He's unemployed and I'm working but he also expects me to run the house - which is the biggest source of our fights that he doesn't feel I'm pulling my weight. I have major health issues so when I come home from work I am done in and can't even make a meal for myself or the dc.
He's self diagnosed with depression and we recently got news that a recent miscarriage was caused by a genetic abnormality - meaning likely he is the issue as I have dc from a precious relationship. However these problems have been long standing before we got that news they've just got worse since.

Basically what I want to say to him is he's a lazy miserable negative shit who needs to get his act together. What actually comes out is "ok"

I'm sorry , it all sounds tremendously crap. And also you sound completely unsupported by him.

It's not okay for you to live like this. Especially with everything else you have going on.

Maybe it doesn't actually need saying. If he needs to be told then it's highly unlikely he will actually be able to change and sustain that change long term . Maybe it's more a case of you needing to keep reminding yourself of it until such time you decide what you want to do.

Why does he expect you to run the house as well as working (especially considering he doesn't)?
It's it because the children aren't his?
And or because his mental health issues trump your physical health issues in his opinion?
This doesn't sound like a good relationship to start with, let alone your point about arguments.
How does he "go off on one" and intimidate you into not arguing back?

Do you really want to be with someone who treats you so badly?

I used to freeze up in arguments and found writing my thoughts down to discuss once the argument calmed down helped.

"we recently got news that a recent miscarriage was caused by a genetic abnormality - meaning likely he is the issue as I have dc from a precious relationship."

This isn't strictly true, chromosomal issues can just be a random chance - the fault of neither party - but an error during the massive amount of cell replication - I had three miscarriages down to chromosomal issues (trisomy) then had a healthy pregnancy and birth.

You have plenty to resent for sure but please don't let the miscarriage tip the balance further.