Frozen turkey breast worry
I don't know if it'll be good, but assuming this time it did actually cook all the way through, it should be safe to eat. Food is safe for up to 2-4 hours in the danger zone, and it sounds like your initial cooking, refrigeration, and second cooking are still within that.

It does sound like something went pretty wrong with your thermometer usage, though. My guess would be that you just didn't manage to find that frozen spot, and need to be sure to try a couple spots and make sure you're getting the temperature-sensitive part of the thermometer all the way to the center of the meat.

It could also be that your thermometer isn't great, and the temperature-sensitive part is too big, so it was in contact with both the frozen part and plenty of warmer turkey outside of that, and sort of averaged out to 165. Or it could be wildly inaccurate! So you might want to test it on a few more things where you have a good idea what the reading should be, and get a sense of whether you can trust it.

And of course, for next time, defrost before cooking. It's hard to get good results cooking frozen food directly, unless it's small enough. (And as you've discovered, a turkey breast is not small enough!)