What a gut-wrenching thing to happen, I'm so so sorry for your terrible loss. I've not lost someone that close before but have a close friend who experienced something very similar. She still beats herself up about it many years later. She said the guilt and pain and what if questions never really go away, but she has gotten better at coping with the suffering if that makes sense. And she says the "rawness" feeling also fades... Eventually. Be kind to yourself, it's still very very early days.