My I went to the doctor and was put on Anti Depressants. My doctor was brilliant. I explained what had happened and how I was crying all the time and not eating and said that I needed to carry on functioning for my then 4yo DD. She prescribed Citalopram and explained that I wouldn't be on it forever, just as long as it took to get me through everything, including the divorce.
She could see that I was shaking, crying, in a complete mess and she wanted to help me. She explained that it was no different to taking any other medication, you take it because you need it.
I never push anyone to take them, but it is worth considering. They help you to feel "normal" again and able to deal with everything.
The pain is indescribable but it will get better I promise. You are in a state of shock at the moment. I went round and round in circles discussing everything with friends. Why did he, how could he, if only, and so on and so on.
Your H has had time to make this decision, he has already moved on and in his head he won't be able to understand your pain, nor will he want to see it because it will make him feel bad and he won't want that.
There might be an OW, there might not be. People who use steroids can undergo a complete personality change. But either way, whatever has caused him to do this, you have to put yourself first and look after yourself. Eating half a banana is great, it's better than nothing. Drink plenty of water to keep yourself going. Biscuits, as suggested, are also good. Little and often, even if you don't feel like it, but it will keep you going.
It's early days, but it's not about him any more, it's about you and what you want. My XH did the same "I might feel differently in 3 or 6 months" like I was expected to sit around and wait for him to decide.
Please look after yourself and visit your GP if you feel that low.