What would you do?

So I come home from school tonight around 10pm. Before I left, my boyfriend said he would be home just watching tv when I got back. Well I get back and he's not here. Can't get in touch with him, called him and texted him and he didn't answer. He finally sends a text at 12 saying I'm fine I'll be home later just relax. But doesn't say where he is, what he's doing.  And he still won't answer his phone. We weren't fighting beforehand, we actually had a great day together. We both had off and he took me out for lunch. So I don't know why he's doing this. Would you be pissed or just say, whatever he can do what he wants? Because I'm livid!! I feel like its so disrespectful. He knows I'm worrying. He knows I want to know where he is. He knows I can't sleep until he gets home. He knows this is going to start a huge fight! I don't understand. He has work in the morning too. I just don't know what to do about this.