Found things on my husbands phone...

So about a year ago I caught my husband on chatting apps such as kik, chatapp, and other ones like that. At first he only admitted to kik and it took me investigating to find the truth of a few other ones on top of kik. Well tonight I was on his phone in his purchase history and saw that he had all those and more downloaded on his phone in the months leading up to our son being born in 2016 (he just turned 2 on Monday). Last year he swore it was the first and only time it happened so I’m just speechless. I don’t know what he said or did 2 years ago...what do I do? I feel kind of sick to my stomach...we have been married 3 1/2 years and have a 2 year old.