I just always feel terrible for throwing things away, even things that are really of no value, not even to me.

That is the worst. I've been going through my house for two years now, with the goal of reducing everything by half or more, and I keep messing myself up. "This ink is perfectly good! So what if you haven't used in in 25 years!" or worse "But you were *really* into that 10 years ago! If you throw it away now, you were either wasting your time then or being dumb now because it's supposed to be important!"

Is there any variation on Freecycle where you live? Giving things you don't need away can be less wrenching than tossing 'em.