How long does it take for a betta fish to adapt to a large temp change?

What the others said is true, the change was too sudden, just leave him alone for a while, keep the lights low and the noise minimal, cover the tank with a towel if you have to. Hopefully he will recover in a week or so. If he does, wait a few weeks and start to nudge the temperature up a tiny bit every few days. His permanent temperature should be between 78-82, but don't rush it. Hope he is Ok!