How do I know when it's over?

I have been seeing this guy for 5 months and I find myself in a tough position. At times he makes me feel like I'm perfect and at other times he makes me feel worthless. I admit the good outweighs the bad but we have had one too many fights for a 5 month relationship... and when its bad it's BAD!!!... I'm out of work, put on about 10 pounds and feel like he is the only good thing left in my life (besides God). I've never been the type to allow any man to have that much control of my happiness, but this is my reality. Should I hold on to him to avoid slipping into a black hole of depression or should I leave him and pray for something better?