You are still early into this. What you are feeling is very normal. Dont be too hard on yourself. You are going to have ups and downs, good days and bad, sadness and happiness.
Here's the thing. You are still trying to get into his head. You are wasting way too much time and headspace on him. Don't.
You cant figure him out nor should you. There is no rationalizing his behavior because it isnt rational. He is in crisis. He is lost. But only he can find his way out of it.
Let him.
Remember, you did the best you could during the marriage with the tools you had at the time. If you knew better, you would have done better. Hindsight is 20/20. Forgive yourself.
Now, you can either get mired in the shoulda,coulda, woulda mindset or you can use it to propel you forward.
First you need to figure out the things about you that need changing. Then get to gettin' on those.
Then you need to figure out the kind of person you aspire to be and how you can become that person.
As for the other stuff, try different things out. Join a club, go for a walk, go to an exercise class, or whatever might seem a bit interesting to you.
Pray, if you are so inclined.
But get to meet IB. Find something just for you that might bring you some peace, some happiness.