I'm not very good at advice giving, so let me tell you about my relationship as it is from both perspectives.
I moved in with my partner several years ago. At that time he had mild anxiety, but he dealt with it by masking, so I didn't really know anything about it. We were both working, had a fabulous life and were happy. Then covid hit, he had major problems with a person at work deliberately out to undermine him, and he went from someone who occasionally needed a day to himself, to someone curled up under the duvet for 3-4 days at a time. Wouldn't eat, drink, or care for himself in anyway. In fact he just wanted to die. I used to wake in the night and check his breathing just in case .
All this caused major stress between us as he would not talk about it. I began to resent him, the major upheaval I'd made in my life by moving 200 miles away from family. All the usual. I spent my life being angry, he was developing more stress related conditions, ranting his head off, and quite frankly I just wanted to run away from it all.
However, I care for him deeply, so I began to educate myself about anxiety and the trauma associated with it. I was shocked, with both it and my own (negative) responses I'd been giving him. We had just been bouncing pain and anger and fear back and forth from each other. Not deliberately, but because neither of us knew a way out or understood what was going on.
Long story short, I began to tell him how his raging really made me feel (ill and scared), and would walk out of the room and wait for him to calm down. Then once he did, I would eventually get him to talk, to tell me why he was angry, and it was often nothing to do with what he was ranting about. He was confused and scared and this was how it presented in him. He then moved jobs which improved things a lot. I looked at how I could better respond to him and support him, and in turn he began to recognise how I needed support too.
All of this has taken nearly 3 years of hard effort. Our lives are very different now and I miss the people we were but am content with who we have become. Through all of it I never lost sight of his inherent kindness, compassion, and willingness to always help others when he could. It annoys me when I read similar threads to yours and often read the 'advice' of LTB. I wanted to leave his behaviour, but didn't want to leave him, the man I fell in love with, for he was ill, not abusive.
Does he know how to help you? Do you know how he needs to help you?
Does he know what you need help with?Do you know what you need help with? Is he overwhelmed with your needs? Do you know what would reassure you and have you told him?
Do you know why he can't take it anymore? Can you find out what it is he can't take and get him to talk about it.
These and many other questions need to be asked and answered.
But you both have to want to do it. Calmly.
I found that the best thing for us was talking. Calmly, non-accusatory, and matter of factly. Just one subject at a time inbetween other aspects of life so that he wasn't overwhelmed. Eventually conversations became less stilted and he opened up to some pretty major trauma in his past life.
We now have a new normal re our relationship. We both like to share time together and take time apart. We listen to each other, recognise our strengths and weaknesses and live life accordingly.
I am not proud of my initial response to his illness. I thought he was doing/saying things to avoid our general life together. A typical knee jerk reaction really and quite poor.
Education was/ is key. I'm still learning. your DH needs to start.
As I said I'm not good at giving advice really, but in reading this you may seem similarities in your own situation, and a possible pointer in where to start unravelling it all. Good luck.