If I were in your situation, I would NOT look at the phone records. Since he knows that trust is an issue for you, a 180 would be for you to NOT look at the phone records. If you do and then you confront him about it, maybe it would be something totally harmless, then you've told him that you did not change at all and are still not trusting.
All you will do is bring yourself pain and anxiety over it if you do look. I've fought with myself over this very same thing.

I also would not go to the thanksgiving at his parents, and I wouldn't give him a long reason either. I would just say that it's probably best that I don't go.
If he is the one that may want out of the relationship, then he needs to see what it will be like without you in his life.

Just my 2 pennies.

Me: 31 H: 32
Married 10 years, together 11
No kids
H moved out to an apt 8-3-13

Experience: That most brutal of teachers. But you learn, my God, do you learn. ~C.S. Lewis