He's prob cheating, right?

So things haven't a been great with my husband ...since I just had a baby 2 months ago our sex life has been non existent ... and we have been fighting a lot over little things...Soo i went thru his phone saw he visited a dating app site.. has been looking at random girls Facebook pages... and just tons of porn... ugh I'm so disgusted with him. I need to confront him but don't know how. I also feel somewhat responsible for what happened because I have had zero interest in sex and have been really bitchy and impatient with him, but at the same time I feel like that's no excuse. Help :(