How to tell if he likes me and how to start a conversation?

Okay so I realllyyy like this guy he told my friend he would hook up with me. But the thing is that he has a girlfriend. They have been goingout for about 4 months. I text him a lot and he puts winky face and smily faces in his texts and he seem like he want to keep asking me questions about my self. And I ask him hbu? Now I haven't texted him all day and I want to text him but I feel lame saying just hi cause I said that about 5 hours ago and he didn't reply so please help sirious answers only please