Should I stay or should I go now?

So my bf and I have been together for about 8 months now and it’s the longest relationship I’ve been in. He’s smokin hot and super sweet but he’s not the most intelligent person... I know that’s kinda fucked to say but he’s the same age as me ( 17 ). He’s had a hard life which totally affected his ability to learn but he’s really behind and he doesn’t really have any ambitions other than being a professional surfer, all he wants to do is smoke weed, party, and hangout watching movies. I’m afraid because I’m now a senior and I want to be successful in life you know? And my parents think he’s going to hold me back in life. Also did I mention he’s gone behind my back and kissed other girls and lied to me and totally lost my trust. I have been really forgiving of the incidents but the thought of him with other girls constantly is in the back of my head, it makes me super insecure and feel like I have to look over my shoulder constantly. What should I do?