I'll never know what happened

I lost my dad on 1st December 2020. In September we found out he had been struggling a bit during lockdown, he had done a good job of hiding it. On 30th November he went missing and we couldn't find him. The police were searching for him. Deep down I knew that night i wouldn't see him again. His body was found the next morning. He had bought some alcohol so he was drunk, and he fell and hut his face on some rocks and landed in some water so it looks like it was an accident but there was information on his phone and laptop where he had been searching the Internet about if doing certain things would cause death. He had also been self harming. He may have fallen and that's what caused his death but if he hadn't fallen into the water accidentally i still don't think he would have came home. I just don't know how to accept it, I'm finding it harder because i don't know exactly what happened. I keep replaying it over in my head when the police officer broke the news then having to tell my brother, my husband, my auntie, family, friends and the hardest of all my daughter. I feel like I'm losing my mind because my brain won't accept that it's happened. My dad loved me so much, he made that very clear so i just can't understand why wasn't i enough for him to live and fight his illness.