He says its not cheatin online with females i feel its still cheatin! Opinions pls?

I have been with my bf for over 6 months now. I relocated my son and i 6 hours away from all we ever knew to be with him. I happened upon some txt on his phone the entailed explicit details reference to a female he had previously dated and slept with. After long thoughts I decided to forgive him main reason is i deeply love his 3 kids and they would b devastated if i leave and with the understanding tht it would never happen again, lastnite I found the same kinds of things on his wrk Ipad this making it the 3rd time i have caught him. He says tht its not cheating for him to jus fantasize bout the females either way i feel it is, but I believe he is meeting them during his work day! Am I over reacting or should i jus pack my things an go back home? Please Help!