Im so upset... Am i overthinking? (Is he really cheating)

So I've caught my sons father talking to people a couple times and both times he was super apologetic and says he wants to spend forever with me... Well the girl I caught him talking to (telling her he was single and we just didn't work out) he changed her name is his phone and I found out... Then 2 days ago he said he was at the bar drinking... I pinged his phone (I have never done this before) and I followed him. He was in the car alone with her. He said he was just smoking a bowl and getting a ride home as they work together... THEN yesterday.. He came home and I noticed glitter on his face and what looked like pink makeup on the inside of his shirt collar... What am I to think... Should I end it? We have a 2 month old together and I'm devastated... I'm lost and I'm thinking it's the beginning of the end... Am I right or am I out of my head?