Why is it so hard to stop checking their socials?

Broken up for 2 months and I've been struggling with what almost feels like self-harm behavior, constantly checking his socials and making myself sad seeing the following go up. I guess I do it because it's the only thing that I have left of him, but it generally only makes me sadder every time. Blocking or unfollowing doesn't seem to help since it's a matter of self control and there's always ways to bypass it.

Recently told me he's happier without me, he's better off being alone and shouldn't be in a relationship and it hurts to think that he gave up. Hurts to hear he's happier without me. Hurts to turn back into strangers. I want to move on and heal but the hope won't leave my mind, even though he's made it pretty clear.