I'm now 62 and I can already feel my sense of purpose waning. I realize now that I'm not going to change the world. My wife died last year and now I can see that whatever I achieve now it will all be forgotten in a few short decades. Sometimes I think "why bother doing anything?". Mostly I keep busy with things that I had no time to do until I retired at the beginning of this year. But, it has to be said that some of these things are just finishing projects that have long been on hold and that I want to finish just for the satisfaction of having completed them.
Sorry, rambling. Intimations of mortality have that effect on me sometimes.
Sorry for your loss, and hope you have friends / family for support.
But, in terms of "why bother doing anything" - well, that is a big bag of worms, which really none of us should entertain as a thought.
In reality, in 100 years just about every single one of all of our best projects / art / websites will be long gone.
And that is ok - we cant have art galleries with 10^12 paintings to view, but I think the point of life is for us as individuals to do what we love, teach and help others and just enjoy it.
So finish the projects you want to do, for the satisfaction of doing it. And if you want, start a twitter account / blog and talk about it there. Chances are someone will get something from it.
That's what the internet is all about - lots of hidden gems and views into what other people do with their lives.
Sorry, rambling. Intimations of mortality have that effect on me sometimes.