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I think you should take a break from browsing through his social media, or what he does online. Focus on yourself, and tending to your own needs right now.
Breakups are difficult, everyone deals with them differently. Your ex may be liking those things, and going on social media so much as a way to escape. I doubt he's happy instantly from letting go of you. 3 years is a long time to be with someone, feelings change and we grow as people and perhaps he needs a break to figure himself out (which could possibly even be the reason for the breakup) but don't let what he does on social networks imply things to you.
I'd seriously recommend getting off of his stuff and his pages for a while. Give yourself a chance to recover from this, and take a break from constantly viewing his stuff. It's only going to put him on your mind and keep making you sad.
Let him be, and you do your own thing. Give it some time. He may contact you and explain the reason for the breakup, but until then focus on yourself and feeling better.