Need advice

Iv been talking to this guy since like July 23rd. Iv been to his house like 4 times ( he lives 4 minutes down the road from me) we've had sex 2 times. I stayed overnight at his house last night but he always invited me over at like 9:00 at night.. He's my cousins best friend and idk how he will react to this but I think he's trying to hide me. He said he won't kiss and tell unless he knows things are serious. I don't know if we are like just fuck buddies or if we are going for something more serious. He works in like the chemical plants. My grandma knows we are talking and last night she was saying that he needed to quit hiding me that my cousin was gonna find out eventually and I just don't know what to do or what to say to him to find out what we are doing.