driving me crazy 😩 why??

I was seeing a guy and really liked him, we are both 19.  First guy in a year I really liked . however he fount out his ex Mrs was pregnant (16) with his kid .. I ended things as I didn't want to be in the middle or get hurt. He got back into a relationship with her too..  he's messaged me loads of time since saying ' I'm not in love with her, but the situation I'm in I've gotta be with her for the kid.. But he keeps trying to get me to meet him and sleep with him still and go on a date with him still  I won't but it's driving me crazy! We had the best sex ever together and I mean amazing and also I really liked him .. Even though I told him I won't meet him whilst in a relationship he won't get the point and finds a way of getting in contact. It hurts me and I crave him so bad ! 😩  I wouldn't do that to his girlfriend, she's young pregnant and I ain't a mug but I feel so pissed and frustrated  !! Why is he still trying to mess with me, fucking stupid lads