IMO 65-70 is not too cold for a betta, however his metabolism will be slower and therefor eat less often. They will eat when they're hungry. Give him a couple bloodworms, if he doesn't eat them, try again in a couple of days. Always soak freeze dried foods in fresh water to rehydrate them before giving them to your fish.
BTW, bettas are tropical.
One time, I was getting about 20 of them for a big
[hr]
, 3 solid colored and 3 multicolored were going in the show before the
[hr]
. I had them in drink cups in order to change the water, clean the bowls, and bag the rest up. One of them got pushed under my bed. I discovered him 3 months later with only a ring of water around the bottom edge of the cup. A couple weeks later he won a trophy and sold for around $12.