I am so sorry for your loss and pain. I am going through the same thing. My husband died on 3/24/17 in a tractor accident on our land. He was clearing some trees in our woods. He loved that stupid old tractor and I keep thinking what if I had just called in to work that day and spent the day with him like he always asked me to do? He would definitely still be here (or so my brain says). I guess it is normal for us to go through the "what if's"...human nature. I have to stop myself because I know that is not healthy and not helping me heal.
I hope you will find some peace, I hope we all do. Hugs to you.