Boyfriend watching porn - 9months pregnant

Michelle
So today I had a weird feeling about my boyfriend. I looked at his phone and notified he had porn hub open. I confronted him about it, and he admitted to it. (Obviously) but stated he was stressed out and needed to "relieve stress" as we had an argument today. 
I'm 37 weeks pregnant, and super emotional. 
I cannot get the picture out of my head and I can't stop crying. I don't know if it's just the pregnancy hormones or what. We have a great sex life. 
I don't even want to be around him because I'm grossed out. Especially because the topic was "step brother fucks hot step sister."
I'm disgusted....