Husband deleted messages

I know many would say IATAH for checking my husband's phone. But when I did I saw his messages with a girl, but I know that he have deleted some because they were talking about something which is not on the ones i read. Part of the conversation was he is busy because he's on holiday (he is home everyday with us) and can talk next week when he is back at work. I did not confront him immediately, and when I did the messages I read is already deleted which makes me more mad because why did he? He said because he knew I would snoop through his phone. He admitted that it wasn't the first time he deleted messages. But he said it was never flirty conversations. Would I believe him?