I recently lost my Dad and I am an only child

My Dad suddenly died of a heart attack last week. He was 76. He was a heavy smoker all his life but seemed okay. He was fully functional until the day he day. Our relationship was complicated but he meant the world to me and, as an only child, he was one of the two most important persons to me, the other one being my Mom. It was the three of us against the world for my whole life. I resigned to my job at the end of last month intending to freelance until I found something better. Now I have to be strong and find something soon to care financially for my Mom. And I have to do this while feeling the lowest I have ever felt in my life. Although we have family and friends no one has offered any help in the past few days. It's all "we are here for you" but no one really is. It's only been a week and everybody has moved on. Not one of those my generous Dad helped when he was alive has showed up to be present. My Mom and I are completely alone and feel so lost without my Dad. I miss my Dad tremendously, I feel horrible regret for not telling him how much he meant to me, for fighting over petty stuff, for not persuading him to stop smoking years ago. A few years ago Dad lost the wealth he once had due to several people taking advantage of him and going through his documents I feel so angry at those people I could explode.
I want to go to sleep and wish so hard that this was not happening. I want my Dad to be here.
Barbara