I am so, so sorry for your loss.
Of course it’s hard to fight back the depression! You lost a parent recently! (Hell, I still have bad days about my mom’s passing, and it was 4 years ago.)
My advice is this: keep moving forward as much as you can, and accept that you are going to grieve and be depressed for a while. It’s awful, but that is the natural process. If you are having problems coping, TALK TO A COUNSELOR. Grief is so, so hard to cope with, and having a professional help you is invaluable. (The first time I went to see a therapist was a few months after my mom had passed, and that made a HUGE difference.)
Again, I’m so sorry for your loss, darling. It’s awful and it hurts, but eventually you’ll feel joy again.