Michelle, this is going to sound harsh but there's probably nothing I know or can say that will make you feel any better. You are reacting pretty much the way most of us would in your situation. It's normal to grieve when we lose someone we thought we loved or that we did love. Don't mean to hint that you didn't. But having been divorced after 20 years, suffered through husband having cancer, lost a 6 month old baby girl to meningitis, lost mother to a stroke and mother in law of 15 years to an accident, father in law to cancer, and just recently my 3 year old grandson to cancer, I can tell you that you will get over this. It is simple-----one foot in front of the other. A little bit at a time, keep going. Don't expect to forget about this hurt-----ya gotta cry your head off, kick the wall, throw stuff, talk about it but then take a deep breath and do something positive. The first day, something tiny that you enjoy or makes you feel better. Or even focus a bit on someone else who has a different kind of grief and hurt,,,,,just for a bit. Each day try to find something good in your life without him. Don't spend time wondering, worrying, thinking, about what might have been, or why this happened because it probably wouldn't make any difference anyway. He's gone and it hurts like crazy. Wish I was there to hug you and take your mind off this situation for a bit. If it helps, come to us like you did and spout whatever you need to spout. It's nice any time of the day or night to be able to talk to us because we don't know you, and don't know him so you can say whatever you want. Someone here is bound to understand and send good thoughts your way.
You might try journaling. I found that when I typed (back when we had typewriters) it helped to spell it all out on paper and when I could face it, burn it and watch the bad stuff go up in smoke. And then try to let it go.