Cheating

So I'm gonna sound like a fool but I found messages on my boyfriends phone to other girls a few months ago which were clearly him trying to move to them asking them for their number but the dates were from we had spilt up but we're newly getting back together from something stupid I done but one was to a girl I've asked him about earlier on in the relationship that he said he didn't like her or its nothing like that but he was telling her he missed her and always liked every picture of her anyway we got back together, I know write mug on my head now but about 10mminutes ago I just went on his phone because he was showing me something on there and I quickly switched to his messages and the first one on there was him asking a girl for their number but he just brushed it off and said its not like that and I didn't have enough time to see the other messages should I take his word for it but he was acting really weird like how he did when I seen the other messages