My dad died on September 14th. How do I deal with the sadness?

He died the day before my birthday. I am the oldest daughter and have been responsible for everything. No one hads helped me. I actually watched his body shut down over a 2 day period where fluid was building up in his body and he was dying. I was the only one there in the hospital.I wake up at 3 or 4am in the morning some days and just start thinking about him. I do not know how to get the last 2 days out of my head. He didnt even look like my dad anymore. His body was so swollen and he was in end stage heart failure. I held his hand through it all every time the hospital had visits. The night before he died, I knew it was soon because ICU let me stay 4 hours past visiting. I went home that night and got a call in the morning saying he had another cardiac arrest and they put him on a ventilator which they were not supposed to do because I gave them the living will and I had Power of Attorney. I went in to the hospital thinking I was going to have to remove my dad from ventilator and wasnt sure if I could. The nurses brought me in to see him. I went in and saw him on that tube and breathing machine. Thinking he was still alive because I saw his stomach going up and down, I kissed him on the head and held his hand, 1 minute later, the stupid nurse told me he died 7 mins ago.. I had no idea he wasnt alive, then when I looked at him I saw how his face was turned. I fell to the ground and started screaming. They had to put me in a wheel chair because I couldnt get up. I hate that the nurses did that to me. I dont know how to get over any of this any more. How long will this take? I cry where it feels like I wont stop some times. I could be doing well for few weeks and then all of the sudden I get really upset again. I miss him so much. I took care of him the last 3 years because of his short term memory loss from previous strokes and my step mother divorced him and I stepped up because he did need some help with small things. How do I get through this. My own blood related sister wasnt even there while he was dying because she was on drugs. My ex step mom gave me difficulty in letting my half brother and half sister come in and say good bye just in case it was really the end. I deal with his death on a daily basis because I am the Executor of estate. I am so tired of all this and need help. Please help me