Is it cheating?

Iv just found out my husband has been sexting another woman. I found out he was texting her a few months ago. He said it was nothing and as he's never done anything like this before I gave him the benefit of the doubt. He deleted her number and that was that untill tonight when I found all the dirty texts and pictures. He says he's been stupid and nothing has happened, just texting but my head is a mess now. We've only been married 1 year! I really don't know what to do 😭