Should I hold this against him?

So my man and I have been together for a year and some months. I was going thru his phone 2 weeks ago and seen who he had blocked from viewing his story on snap and seen this chick. i went to investigate and seen saved messages from the first month we were talking, talking about let’s hang out i wanna see you i’ve always liked you. And all this bullshit ! but that’s it. I noticed the last time they sent each other messages was 2 months into our “relationship” . Mind you this was already after we had raw sex and all and he even told me he loved me.

Now we’re in a really serious relationship I moved into his parents home and now i’m almost 4 months pregnant.

Long story short I think I shouldn’t be TOO upset because it happened earlier in our “relarionship” and he didn’t officially ask me to be his gf until 3 months into us talking. but still we’re exclusive already.

I know people change and I talked to my sister about it that it isn’t the CURRENT situation. He’s changed a lot for me I believe but still it makes me look at him differently now because i thought he was a little saint. He said they never actually went out because SHE HAS A BABY DADDY. Smh.

Any advice? Ugh! I feel like it’s my fault for looking through his phone! He hardly ever goes thru my phone. Maybe once in a while only because I go thru his way more often.

I WILL ADD:

It gets me upset because he’s judged me so much on my “past” even because i texted his friend from work for a little bit (less than a week) way before me and him started knowing each other. He always held it against me so for me to see this makes me think damn your no better than me!)