Wtf I can't believe this

Me an my man have been talking about marriage and TTC for a little while now. I'm finally late. Last month i was extremely light for the 4 days, now 6 days after my next ones supposed to start still nothing. I should be so happy right now but then i find him on some dating site online. I'm so hurt WHY NOW. I don't know what to do if I take this test an it comes out POSITIVE WTF. I can't stay with a man that's cheating.