My honest opinion? It sounds like you want to put you head in the sand and pretend things arent happening. I think it's OK to say youd like some more time. But I think it would have been better served to simply say "I'd like some time to consider this. I will discuss with my lawyer and decide what makes the most sense for me."
I feel like just saying "This is too fast. I need some time to think." makes it sound like you are in denial or are weak. I think it's good to make it clear that you dont want to reply immediately because you want to consider things but also you need to discuss with your lawyer.
For example: That is a lot to process and I'd like to think about it for a while before responding. This is honestly going so fast and I want to think about things before responding what is the benefit of the part in blue? What does saying "it's so fast" really mean to her? It's saying that you think with enough time, you can change her mind. That you arent ready to do anything "irreversible" because you dont believe this will happen. It feels fairly invalidating to me. Then, after the blue text, those words are just repeating what you already said.
These are such huge life changes I need to think I can't believe ur trying to discuss this over txt I don't mean to sound accusatory either I understand u have very valid perspective on things As for this message, I dont know what you were trying to say. You didnt really reply to any of her comments/questions. If you were uncomfortable with texting, maybe say "let's discuss by phone" or "can we meet XXX to talk about this more?" It reads like you dont like what she's saying and so you are lashing out. It reads chaotically. As for the blue part, that sounds like a textbook line, but Im not really sure how it applies given the context of the conversation and what you had already typed in this message.
Just my thoughts. To me, it reads like an ostrich burying his head. How can you take charge of your own actions through this?