Am I jumping to conclusions !

My husband has been obsessed with a game on his phone for years and I thought it was a load of men on silly war game, my toddler gave me the phone to put his app on and I innocently opened phone and it went onto group me where there were private messages between him and another women I started reading him asking her if she was behaving herself etc... His screen shot is old of him in better shape and there was kisses on the messages , I was so mad  I threw the phone at him and he looked white as a sheet then quickly deleted their messages and told me it nothing why was I going through his phone I said I wasn't it opened up , he got angry and tried turning everything on me! I'm so mad I didn't read more do U think it innocent . Please help I feel sick right now iv two boys who need me, am I wrong ?