Forget him... he's playing you and her. Move on.
He's playing dangerous mind games. It's going to hurt regardless what you do. I say back out now before it hurts more later.
There's the board game "Life'" where we all have cute little cars and acquire lil peg babies and make money and it's all fun. The real game of Life is not so fun and the more games people play, the less fun it becomes and the more it hurts....
Leave him alone. If he has a girl, that is a stop sign.
keep your distance and watch for his advances towards you ,,,orientation ,, tilt ... you will be clear very soon.
He's the one who's confusing and sending nice signals! Not u. He has a girlfriend. If he didnt he wouldn't have posted about it online. I think he's sexually attracted to u and is using u for sex. If a guy likes u for more than just a sex doll, they'd call u, take u out in public (this also would show he doesn't have multiple girlfriends), be nice to u, do u favors and buy u a gift without asking for anything in return (guys always give gifts to girlfriends)
He sounds like a vampire to me.