First of all, don't be level 12. That's way, way, too low a level. He is level 15. Enemies who are a higher level than you are do extra damage to you, and he's a horrible pain and very dangerous even if you're the same level.
Even if you beat him, the next area has enemies of level 16. Go back to Broken Valley and try to reach level 15. At Level 15, you'll get some very helpful skills.
Second of all, what skills do you have points in? That is important information for us to know if we are to be any kind of help at all.