Shit happens. Either adapt or move on.
I was a Zilean player before his rework. I changed to Bard because Zil Q was completely crippled by bugs for a year.
I was a Heim player before his rework, and still am.
I was a Zyra jungle player before her rework, and I dropped it afterwards because they unintentionally gutted her clear's reliability.
I was a mastery 7 Urgot before his rework. Still play him, and I'm not too bad at him, but he's not the same.
I was a mastery 5 GP before his rework (back when that was the highest it could go). Can't play him well anymore, so I rarely do.
I loved playing Evelynn mid before her rework (even right before it dropped), but I can't make it work anymore so I don't play her.
I was a mastery 7 Taric before his rework, and still play him a lot.
All of these reworks were (eventually) good changes to the game (except Zyra, whose rework did pretty much nothing either way), and that's true regardless of whether I and their other old players stick with them.
It's happened before, and it'll definitely happen again (Teemo, Sona, and Morde for me), so learn to roll with the punches.