Am I being completely immature/crazy?

Okay, so long story short:

My boyfriend and I just made our long distance relationship not long distance. I'm American and he's British. We've been together for over a year and I just made the move over to be with him.

Basically, he keeps this log of every single day of his life. The other night, he left me his laptop while he went to the pub with friends so I could do some work and I got curious and invaded his privacy (I recognize that I shouldn't have done that - especially since he entrusted me with his laptop) and read some of the log.

There was another American girl he really liked that I already knew about and I got curious and read a bit about her that he wrote before he even met me.

Basically, he told me before that they only had sex once. In reality, they had sex many, many times. He went really in detail in the lot and now I have awful images burned in my mind of them together, and I feel especially hurt since he told me they only had sex once.

Additionally, he was writing about another girl he never told me about and saying things like, "oh my god *name* is so hot", etc. I know it was before he met me, but it's really messing with me.

I think it might be because I always thought I was special.

Oh, a few days before that, I also saw over his shoulder those two aforementioned girls in his recent searches on Facebook. I asked him about it and he said, "to tell you the truth, I just decided to see what they were up to." Once again, this was before I read his log.

So, after reading his log, I checked his history on his laptop to see if this was true and that really was the only time he's ever looked at them on Facebook.

All this wouldn't bother me TOO badly if I didn't also read a bit of his log from when we were dating. Granted, most (actually... almost all) of it was about me and very different from how he ever talked about the other girls (from what I saw from what he said about them - like I said, I only read a bit), but there was one bit that really got to me that he wrote WHILE we were dating.

"I just cried. I cried because of *other American girl* because well she was a lovely person."

WHILE we were dating.

Am I reading way too much into all of this?

He asked me to move over and here I am. Shouldn't that be enough for me? I'm 25 years old. I shouldn't be this insecure about my wonderful relationship.

Am I just being ridiculous, immature, crazy? He wrote that sentence almost a year ago, he wrote about the girls before he ever even knew me, and he just happened to look at those girls once on Facebook. And he wrote these things in a private outlet for himself. That I delved into.

Am I just insanely insecure?