I'm so very sorry for everything you are going through.
I too have lost people who have been very close to me, but no one affected me like the death of my mother. Like you my mother was not just my mother, she was my best friend, my confidant, in a way - my soul mate. I felt like we had known each other for many lifetimes. My mother passed in 1993, after a battle with cancer. I was her caregiver, so when she died, my entire life changed. I know longer had the person I cared most about in this world, and I no longer had a job. She was my job for about a year.
Even now I have a hard time talking about her without crying. That bothers me sometimes, because I'd like to be able to talk about her with joy and rememberance. Some days I can, but most days I still grieve for her so much.
I even went into therapy because people kept telling me that my grief wasn't healthy. My therapist told me that my relationship with my mother was very special, and unilke most relationships. She told me that my grief wasn't something I should be ashamed of or try to hurry. That I will probably always grieve for my mother. It gets easier. I'm not consumed with grief all the time like I used to be. But somedays, it's harder.
Grief is different for everyone. My advise, don't try to dismiss your grief. Just try to find a way to walk with it. I actually started to feel guilty when I started to feel better. I felt like I was betraying my mother. I knew she wouldn't want that. So I continued to try to pick up the pieces, and remember the better days. When you can remember the good times you had with your loved ones, instead of the time of their dying, it gets better. Try not to think of the what ifs.
Perhaps something good can come from their deaths? My mother died of lung cancer, this caused my father and other family members to stop smoking. It also made me a huge advocate against smoking. I like to think that she didn't die in vain.
If you need to talk, please feel free to send me a message. I may not be able to make it go away, but I'm a good listener. And sometimes that's what you really need, a person who can listen, and who isn't involved with the situation.
I hope you have better days.