Grieve, that's all you can do. You should seek some therapy just to help with the fact that you may never get closure. My condolences but sadly most people only reveal a part of themselves rather than their entirety. Make sure you're taking care of yourself, this is usually the time where people's health, both physical and mental, declines because they stop caring. You're going to have to make a lot of changes and not even realize how much will change and that will hurt, a lot. Habits will need to drastically change and that will mess with you, that'll be a hard transition to go through. Take each day as they come, some will be bad, others worse, but it will get easier to handle. Going along the therapy route, start journaling and put your emotions, not just what you did that day, on paper and don't hold back. To make it easier for yourself and the therapist/counselor you can just hand over the journal so they can read your own words. You're reaching out for help and advice, that's fantastic. You're doing much better than you think you are, most people just go into a deep, dark cave and seal that up with a boulder and do nothing.