I feel like my bf is cheating

ME AND MY BOYFRIEND GOT INTO AN ARGUMENT LIKE THE MANY WE’ve been having I TOLD HIM IT WAS OVER RIGHT before HE WENT TO WORK AND NOT EVEN AN HOUR LATER I FOUND OUT HE ENDED UP MESSAGUNG ON INSTAgram 2 of the girls he used to mess around with ON THE LAST BREAKUP WE HAD ( bc he cheated ) before. This wq

-HE WAS BOTHERED BY EVERYTHING I DID and started arguments over it .

- HE GOT BOTHERED BY ME BEING ON HIS PHONE WHICH HE NEVER DID

-HE STOPPED PAYING ATTENTION TO THE WAY I TRIED TO GET HIM TO LOOK AT ME HE DIDNT REACT AND GE USED TO GO CRAZY-EVERY TIME

I convinced myself it was my fault bc I “broke “ up w him but c’mmon we have a kid and we live together I can’t just break up with him like that and mean it

Now that I found out about that he’s been trying to act the whole opposite