Reccomend a book for tremendous grief and loss.

Trigger warning: death.
I’m so lost. My boyfriend proposed to me in Hawaii. Then only hours later while swimming in the ocean,I got pulled out in a tide and he came into save me. He drowned and I preformed CPR with others for 20 minutes before the ambulance got there. I’m living with the guilt of his death along with the death of him and the loss of my future. I don’t know what to do but I’m so incredibly lost. We lived together for 4 years. My everyday life has been turned upside down. Please recommend a self help book or biography or fiction book about loss that made you feel better, that made death make a little more sense.