OP, I'm just copying over a few things I said on your previous thread, just in case you need it.
I think, in the end, you loved what he could have been if he had been a different person.
And the fact that one of his first thoughts was that he could find someone else, shows you how quickly he turned his mind to "me me me, what's next for me?"
Please try to remember this when, inevitably, you start wishing things had been different and how much you loved each other. This one is not partner material.
Right now, your brain is in shock and in survival mode, so your heart is leading the charge and is feeding you all sorts of lies. It feels "better" and "easier " that way. It isn't. That way madness lies.
You will cry a lot, and you will start to bargain with yourself. What if he just...? What if I didn't need...? What if he just needs time...? Why don't we just try...?
You need to ignore EVERYTHING your heart is telling you right now. Listen only to your head. If you can't hear your head, let all these wise women on here do the hearing for you.
He will not change.
He will promise he will change.
He won't.
He will bargain and promise, and when that doesn't work he will threaten.
In fact, he has already started to threaten you.
In the first few reactions yesterday, he showed you who he really is. Believe your eyes and ignore your heart.
The person you wanted him to be is either not there anymore or he never was that person.
One day at a time. Think back to how angry you have been, how chaotic your life has been, how unfulfilled you have felt. Is that the life you want to go back to? Is that the kind of life you would want for your best friend or your sister?
You cannot have what your heart is telling you that you want, without also having all those other horrible things that he brings into your life.
You will feel terrible, sick to your stomach, panicky, "what have I done" over and over and over. Until, a few weeks or months from now, you will wake up one morning and it won't be the first thing you think about. I promise you, THIS WILL PASS.