That does suck! You definitely need to take care of yourself financially and make decisions that give you the most options and control of your financial situation.
I dont think it helps to stay angry - it might be normal and healthy to be angry to start with, but move towards getting over it, so don't call your stupid husband too many names!!
What's your plan? I'm sure you are forming an idea of what you want to happen.
This is an opportunity to listen and validate what is going on in H's life. You might be the one person that he can open up to and share how stressed he is with finances. Also great opportunity for you to thank him for trying to resolve financial pressure on himself and you, thank him for trying to look after you, admire him for making hard decisions, admire him for not just letting things slide but being proactive. I know its really tough when he's making choices different to the ones that you would make, but this is an opportunity to respect your H and create a positive interaction. Which will be a real 180 - he's expecting you to be upset, which is why he probably sent you a text message so he didnt have to deal with your emotions. And possibly OW is already telling him that he isnt doing enough, he's inadequate, he needs to look after her more.
Men's egos are fragile things.
(The turning point in my DB-ing journey was when I got to tell H that I was proud of him for making the decision to separate, and that I knew it must have been really hard, and that I admired him for being true to himself blah blah blah. I could tell that I was the first person that had 'understood' how hard it had been for him too.)
I agree that this is a major decision that needs to be discussed, possibly with someone else as a 'mediator' that is able to look after you and your financial interests.
You do have plenty of time - you can always stall too and say you need more time to think about it.
I think its entirely possible for you to go into this situation with the goal of creating a win-win. Neither of you has to lose. It will mean that you need to really really listen to what his main upsets are (often not the surface ones). And also stay strong on what outcome you really want.
Try and keep the emotion out of it and treat it like a business deal. Men have the upper hand in these situations because they can separate emotion more easily, so having an older male member of your family to guide you through this might be helpful??
Thinking of you Julia - thats a really hard situation, and because H & I were cashed up when we separated it was so much easier to split things in half, and caused no resentments. In fact we've tried to outdo each other being generous!! 'You have that', 'no, you have that'! So I don't really know what you are going through, but I think you are amazing! And feel free to ignore any advice.