Sudden Loss & Not Sure I'm Coping

I have never been in a situation like this before- I am sorry if this is long. My partner and I rent a main floor apartment, our landlord lived in the entire top floor of the house. My partner lived here for 2 years before I moved in, he knew our landlord better- I would call them almost friends. I knew the landlord but it was more of an aquaintance type relationship. He was always very nice, he reminded me of a friendly lumberjack. 
Last week he took his own life, in the apartment above us and he was there for 2 days before his father and police found him. He had been struggling his his mental health for years, but even more so for the past 9-ish months after his live-in girlfriend broke up with him. In the winter he was commited to a mental-health institution for 30 days (but talked his way out of it after 18 days), his Dad helped him re-do the apartment (he trashed it before- holes in walls, writing all over walls, a mess everywhere), and his Dad also helped him get a job to give him stability and structure. He seemed to be doing better....not back to his old self completely, but getting there. My partner would occasionally check in on him by text. 
We were both home at the time he was discovered. Our street was blocked off with every type of emergency vehicle. Our walls/floors are thin...I heard his Dad find him. I was in a bit of shock for the rest of that day, my partner was as well- we stayed at a friends house that night. It did feel good to be home...but also different. Knowing that for the two days he was up there we were just living life, happy, care-free...we ate, we laughed, we threw carrots to the deer in the backyard...and all the while he was up there. 
This weekend I was home while my partner was at work...it felt weird, silent. I felt like an intruder who doesn't belong. I've had constant free-floating anxiety ever since. On the one hand, home feels like home (warm, cozy, ours) but on the other hand it feels like a foreign place. Before, we always knew he was up there...he would come at a moments notice if we ever had any issues, he was an amazing musician and we used to always hear him playing piano or guitar and it was beautiful. I can't stop thinking about how while we are in our apartment, watching tv, etc, his place is sitting there empty and sad. We may have to move in the coming months...his Dad said we don't have to worry for the next few months but he has to figure out if he wants to keep the house or not. I love our apartment....but moving may be good as well, so we are not reminded of who he was at the beginning and the decline we watched until it ended. I, of course, am heartbroken for his family and friends. 
I just feel...empty and anxious and I don't know how to ever feel 'normal' again in our home. I'm sad he's gone, I'm sad about the way he left, and all of the lives that have been affected by his passing. I feel selfish for how this is affecting me when I didn't know him as well as others. I hate this feeling of emptiness and anxiety-  I am not quite sure how to work through this, or if it will just linger here for as long as we live here (moving is possible, but not ideal at this time)
If you made it this far, thank you for listening. At the very least it felt good to type all of this out.