My then husband's behaviour caused me to hate him for the last few years of our marriage and I would often daydream about what my life would be like without him in it. I therefore couldn't understand why I was so devastated, despite my relief, when he finally left.
I think it's a process you have to go through, especially if you have been together a long time. You have to mourn what you should have had, the future you should have had, the partner he should have been.
You have to get used to your new life, be kind to yourself as you do so. Do little things that will feed your soul, make choices that you want to make. You know those little (hopefully) things you stopped doing because he wasn't keen? start doing them again. Eat the foods you stopped eating because he didn't like them, watch the programmes you didn't watch because he whined all the way through.
You'll probably find your mind on him a lot of the time but that will reduce. If it helps to write things down, do that. I found something the other day where I'd written what I was feeling at the time and was pleasantly surprised to not remember those feelings and to realise how far I've come.
Set yourself a target to find at least one moment of joy every day, whether it's noticing the colours on a bird's feathers, listening to bird song, noticing spring bulbs poking through the ground. Nature is very grounding. You will find the non crying time overtakes the crying time, sometimes just a minute a day, sometimes more, but you will get there. And we're here for you, if you need us, along the way 