Anyone have trouble sleeping after losing someone?

My old man passed away unexpectedly a little over a month ago, he had a stroke in the gym. He was 80 and a pretty healthy, active 80 year old.

I'm 32, the youngest of his children. It was a shock to all of us and I have some regrets, I didn't get to tell him some things, that he did good by us and so forth but that's probably something that I will be able to live with, the big problem is my sleep and mental health.

So, I've been feeling this heartache ever since, a severe anxiety kind of feeling and I have trouble sleeping. When im almost asleep my mind plays out how it would feel for my father to pass away and it's like I get a glimpse of the void, I get the feeling im leaving the mortal realm and it's so uncomfortable. Usually I get up with a huge adrenaline surge and it takes a while to calm down enough for a second try at sleeping. I also obsess about my mortality and get constant play through in my mind about various scenarios of my death or someone I love and it just feeds the void inside me.

Anyone have something similar happen to them? Any recommendations for improving sleep quality? I need to make every minute count as I am running a very busy business and have 2 young children that don't give me many chances to rest. I need sleep for my mental health to improve, and for me to continue functioning for my family.

Advice is welcome.