Am i not good enough?!?!

My SO and I were having sex. I thought things were going great and then I hear this moaning coming from somewhere and apparently while behind me is watching porn. I mean I know I'm fat and pregnant and probably not attractive anymore but it really killed my mood. Like I'm not good enough or sexy enough for him. And right away he came and was done. I couldn't even enjoy sex or reach an orgasm because of this. I feel like I'm not good enough now :/ I don't know how to tell him without making him feel bad