What should I do or should I do nothing?

So last night I found out that the guy have been seeing for eight months has a four month pregnant girlfriend. My friend saw them and told me about it. I haven’t talk to him in over a week anyway because we had an argument over something he promised he would do for me and didn’t do it. I’m not sure if I want to text him and tell him I know about it now or if I want to wait until he text me and tell him all about himself or should I pretend that I don’t know about it and go to his house when he invites me over and let him see the hurt on my face when I tell him I know. I can’t stop crying my heart is broken mainly because I told him how I just got over a heartbreak when he first started talking to me.
What should I do or should I do nothing?
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