Feeling sad is part of what defines us as humans, so your feelings are absolutely valid. However, you don't want to wallow in so much sadness that it keeps you away from the things you love. Whenever I feel sad about a lot of things, especially those beyond reach, I take a deep breathe, and say "this too shall pass", and I kind of feel relieved after.

I like that you are able to express your feelings indepth in this writeup. Speaking up or writing atimes help to reduce the burden of the sadness.

Sending you love, light, and hugs.