Struggling to communicate in a new relationship

I've recently entered into a new relationship with a fantastic person who has ADHD and autism. When we are together, and can talk face-to-face, then the relationship is one of the best I've ever had. She is kind, caring, a fantastic Mum, and everything I want in a partner. She is also incredibly strong, and very independent.

However, over text she has a tendency to be incredibly aggressive and defensive, and no matter what I respond with it is never the right thing. I feel like the conversation is predetermined in her head, so I could say nothing and still get shouted at. Recently we had a rough weekend, which was no fault of anyone's, but it was an incredibly stressful situation for her, to the point that she was starting to break down. Since then, she has been stuck in a loop of telling me I don't care about her, and being angry at me and disappointed in me. Yet, when I reach out to support her it only seems to make things worse. She feels like I'm not listening to her, yet is reluctant to share with me. She also has a tendency to accuse me of lying. I am potentially autistic myself but have not been tested, so I do struggle with reading emotions over text and I communicate poorly sometimes. I shared this information with her yesterday, and she felt as if I had been lying to her and deceiving her for the entire relationship, and because of that it invalidated everything I had told her previously. Though, I felt like this was my choice to share when I felt comfortable and had nothing to do with how I feel about her.

She will also regularly just say she's leaving, or say"Goodbye" in a message to imply that the relationship is over. Yet, will continue to respond, though these will be hurtful messages. I feel like these are cries for help more than anything, and she's used to people just giving up on her. I spent 5 hours on the phone with her yesterday, just trying to talk to her and reassure her, and it barely made a difference. The relationship was genuinely saved when her Son started making us both laugh over the phone, and it was like everything was back to normal in an instant.

I care about her an awful lot. How do I reassure her that I am here to support and love her to the best of my ability, without potentially causing an upset? I've been really trying, and fighting so hard for her, and us. But, I feel like she hates me for it, and there is only so much apologising I can do.

Any advice would be greatly appreciated, thanks.