You need to figure out for yourself what's important and what's less so. Do you have the time and energy to sort out where your equipment and music library will go? From what you describe that's the real issue.
The unused equipment and maybe the secondary systems could be parted out now. The same for most of your music collection. If you want to give some things to people you know, then you should talk to them now and make the arrangements. For your high end/high dollar equipment you should discuss with your family the best ways to dispose of them. It should be no different then discussing real estate, vehicles or investment portfolios with them. You might prearrange working with a dealer to help on this.
Not to sound macabre, but picking out your wake/sitting/funeral music can be a fun project. Music has the power to bring everybody together even under the most difficult circumstances.
Best Wishes