Your story sounds very similar to my own in that the one person who helped me really get into roleplaying actually died a few years back. He was a hobby writer and just generally creative but suffered from a few medical problems. Oddly enough it was actually a brain aneurysm that killed him, something that had little to do with his medical issues.

The difference between you and me is while we both had friends who were a part of our lives in writing, you've associated yours with the hobby directly while mine was in the aspects of association with similar interest. Because of this you've sort of created this conundrum where your act of writing reminds you of that person and that is something you may need to change over time. I'm sure they would not want you to stop, but you have to also realise that your skill is of your own and if you are forcing yourself to be here then it's something deep within you that has to change.

The unfortunate part about the world is that everything only has a limited lifespan, whether it's friends, communities, or even interest. It is what makes us want to pursue an interest, a person, or a group because we know there is a limited time in which we can do so. So when it ends... You sadly either have to reignite the fire, or move on.

Sorry if this does sound a bit grim and harsh but there's just not an easy way to convey the message. I offer my sympathies for your trouble but the solution I offer isn't gonna be a magical elixer.