Found out boyfriend was sexing another girl

I'm so devastated right now I seen where my boyfriend was sexing another girl and she was doing the same. This is one of his old fuck buddies. I'm currently pregnant at 11 weeks with his child. He said it's nothing but I give him sex and I work and he works a different shift he 8 to 6 where I'm 4 to midnight but I make time when I come home and in the weekend. Am I in the wrong for thinking that's cheating