Why won’t my (ex)boyfriend admit to cheating even though he’s been caught?

I went through his phone because I had this gut feeling he’s been cheating and saw where he met up with a married woman at a busted down motel on Monday night. This was literally 3 days after I decided to give him another chance and he begged me not to leave him again. When I calmly asked him about it he was silent for a few minutes like he was thinking and then said it was her birthday and she was having a hotel party. He called his mother, brother and cousin so they all could confirm she’s just a friend and has a husband. He then flipped out and told me I need therapy and I broke the trust. Now obviously I don’t believe any of this shit but our relationship is done so I don’t understand why still lie and try to make it seem like I’m crazy. It’s driving me insane and starting to make me doubt myself even though I know he cheated. Someone please tell me I’m not crazy.