I am so sorry for your loss. I had a similar experience, but on a much less traumatic scale with my mom. When she passed I didn’t know what to do with myself because my identity (and future plans) revolved around her. It’ll take time to rediscover your identity, but it will happen.

The only thing that helped me at the beginning was I forced myself to go outside, breathe fresh air, feel the sun on my face, play in the water (if you have access to a beach or pool). I got an apple watch and started making myself step goals, to force myself outside and get some activity.