I don't know how any of that can be or how to do it
The first step is to take care of yourself physically and mentally. When our thoughts are dominated by a single thing, we can lose sight of ourselves. So please do not do that.
You have some books coming in the mail, and you can read them when they arrive. They will give you insight into what happened, and how to avoid it happening again.
I get the impression that his struggle is internal, and because of that, you are almost a bystander. You want to be able to help him, but at the moment he has retreated into himself in the way that men do when we are in pain, and trying to fix it.
The worst of this stage will pass, and we will do what we can for him in his thread here. He has some very good forum members rooting for him and offering him advice and a sympathetic ear.
If you are worried about him, do you have any mutual friends who could call round and see how he is? He mentioned that he is basically alone, a long way from his family and friends, so it would be good if someone - maybe even your Dad - could call round from time to time to see how he is.
In terms of messaging your husband, I think that his pain right now is probably overwhelming, which is why he does not want any communications from you. However, if it will help you, you could send one text - and only one - with a simple message, like "I am so sorry". Do not mention love, because that will just trigger him. And then let him be for several hours.
Tomorrow, you could message him to say something like, "I am worried about you. Please talk to X (a mutual friend, or his friends). I am ready to talk if and when you are. I want to give you space and respect your wishes, but please know that you are in my thoughts 24/7".
At the moment he is not ready to discuss anything deep or emotional. That is the stuff that is hurting him, and so he is trying to get away from it. That is why the tone of the message I suggested is practical, but brief, and not touching on anything deep that might trigger him.
I am sure that you are suffering like never before, but please do not mention that to him. It will be a huge trigger for him. By all means discuss it here, because there are already some terrific former wayward wives involved in your thread, and they can be a great source of support.
Maybe at some point over the next few days you could take him some groceries, and ask him if there is anything that he needs. Do not attempt to draw him into conversation. He will probably want to keep his communications brief and limited. However, little acts of care and asking about his well-being will not go unnoticed, even if he does not acknowledge them visibly.
The word 'love' is likely to be a trigger for him for some time, so where you might want to say, "I love you", change that to, "I care about you". It expresses your feelings, and it does not provoke the pain driven knee-jerk response of, "If you loved me, the you wouldn't have done x, y, or z, so don't even mention that word to me".
A journal is a good idea. It will help you get your thoughts in order. And if you have supportive friends, talk to them. They can help you get through this.
These are my immediate thoughts, such as they are. I hope that they will help.