Horrible dreams, please help..since grandmother passed away

My grandmother passed away mid may, my best friend who lives with me moved, and my boyfriend broke up with me, I believe my mother is now cheating on my dad and we have to sell the house and move…theese are all the events which took place since my grandmother passed away. Well at night a lot of the time I find it hard to fall asleep, I can be super tired but once I lay down I’m wide awake. When I do Sleep I dream of horrible things about my grandmother…like her comming up to us and telling us we buried her alive, or being at her funeral and kissing her and her waking up. Her funeral was the first one I have been too and it was an open casket, Before they closed it I kissed her goodbye…me and my sisters all placed an envolope with letters of things we wanted to say to her on her chest with lilocks attached to them becuase they were her favourite flowers…at the end of the funeral we all talked and found out we all thought we seen her breathing because the lilocks appearded to be moving up and down as if she was taking breaths the whole time… Please help me over come this, Since she left my life has flipped upside down…so much stress…My mom says its just becuase I dont want to accept that she’s gone…I know shes gone I just wish she didn’t pass away… please help thank you