You know, happiness is never as fake as we would think it is. Of course you force a smile once or twice but then it becomes genuine, it comes more naturally. And trust me, I had my dark times and know what "fake happiness" is, and that after a while you'll recover, just "be gentle" with yourself xD
Playing video games helped me the most during those extreme times of mine, it took my mind to other places and I enjoyed playing~ The enjoyment was real, so I knew I can recover.
Also, it's ok to be sad/feel down from time to time, we humans are simply like that... Don't judge yourself too hard on that, ok? The sun will shine again, just be patient uwu