How to get over grieving?

I literally have been plagued by certain instances in my life for years. One instance was when my grandfather was dying of cancer in the hospital, I was two at the time, and although I'm seventeen now, I can still hear him moaning. I'll even tear up sometimes. Other times, it's over one of my past pets. My second cat was run over when I was eight, as the neighbors were putting up Xmas lights, and she was curious and crossed the road to see. When people use the phrase 'Curiousity killed the cat', it reminds me of her and I get upset. We had a kitten at the time who was her constant companion, he spent months looking for her, crying out for her. I can still see him in my head and it's enough to make me cry. Another time was when I was eleven, I had had my conure for about six months and he got out of his cage one night [undid the lock], and crawled into my bed. When I woke up, he was lying a few feet from me, still as anything. HIs death was confirmed by my mother and I freaked. People would say I rolled on him, or stuff like that, but I know that's not what happened. He was such a small thing, he would have showed signs of being crushed surely. There were no external signs of trauma, it was as if he peacefully died in his sleep. He was my best friend, as I always had trouble making 'people' friends as a child, and I just feel horrible. We did not have an autopsy performed. Please, do not give me the 'they're in a better place b.s., cause I do not want to hear it. I just want some genuine help, feel free to message me or whatever.