You have so much in your life that must be pretty overwhelming, both of you do. But this behaviour of hers is making things worse for both of you. Something has to change, something's gotta give. The way you both communicate with each other, the way you're both managing the stress of your child.
I agree that both of you would benefit from having a supportive T. But at some point, maybe a sit down and a couple of calm conversations about planning some changes in the way things are being managed. What things about your situation need to change, and how are we going to make those changes happen? Planning some practical things might start to make the whole situation seem more hopeful, for both of you.
For your own mental health? Having a conversation with your spouse about boundaries with communication. Does she really want divorce? If she does, yelling at you about it when things are out of control isn't the way to have that conversation, and if she doesn't want divorce, then telling her "I need you to stop saying that, period" seems pretty reasonable.
And definitely like
@Fadeaway 's suggestion of going for a walk. Get some space between the both of you when things are starting to get out of control. Walking will also get the breath regulated and help your brain get back to a regulated state where you'll be better able to cope much quicker.
No one expects you to be able to tolerate your wife getting angry and threatening divorce. But some action is going to be required to change the situation. It's not fair. But it's time to make some changes, and those changes won't happen on their own.
It must be pretty overwhelming, so try and be gentle with yourself.
