Guy I like is lying to me, please help!?

I met a guy about three months ago on a messenger app on my phone, who happens to be in my school but a year older. We got on really well and eventually we met up. He didn't tell me he had a girlfriend and he apologized for being a 'dick'. When we met up we got a bit drunk and he minded me all night, and ended up cheating on his girlfriend because we kissed. We got on so well in person. He's such a sweet guy and he told my friend he really liked me and his current relationship wasn't working out and how he doesn't think it's meant to be since he likes me now. So basically, he told me they broke up last week only to find out from my friend today that they are still together. We're always texing and we flirt a lot so it's still cheating. His girlfriend does not know about me but she knows he did cheat on her and said I was a random girl. We're planning on going to lunch sometime soon.

I don't know what I should do now, should I just keep the texting going normally or say something about it to him?