I am sorry for you loses.
It does get better, I lost my oldest son to a car accident when he was just 19. Unbelievably painful. Slowly but surely the pain subsided and the good memories remain. My wife of 25 years died in January of 2009. I was one lost man, lost my focus for a couple years. The pain has faded, the good memories remain. From time to time something will trigger my grief, but I think of the good they gave me and go on with my life, knowing that is what they would want for me.
You can do this. You can be happy and love life. Their memories live in you. They helped to make you who you are. The ones you loved and who loved you would want you to be happy. Honor them in your life