I Am Dealing With Grief

My best guy friend suddenly passed away from cancer. He was only 25. He had luekimea. It hurts so bad. It had been only four months. I've known him since I was 8. It hurts and I feel like crap. I've gained a lot of weight and my doctor cussed me out for not following her diet plan. I just don't wanna do anything. My dad said it's okay to grieve but don't stop living just because my friend is gone. I have to remember that he isn't coming back and I need to move forward and take care of myself. My dad is understanding but not the emotional type of person. I'm very emotional so I don't really talk to him about my feelings much. I don't even talk to my own family about it. I just talk to my friends and best friend because we all know him. Is that normal that sometimes we can't even talk to our own families and talk to your friends instead.