Tinker,
Just because of what your boyfriend has done why do you want to suffer and put everyone around you in pain? By harming yourself, you'll only be stalling the heart-break momentarily, you will regret it later on and still be in depression.
It is not always you, many people go through very similar phases in their lives. Two of my best friends went through this exact same situation. But they didn't give up, they were devastated and heartbroken initially but with time, support and faith they picked up all the broken pieces and moved on with their lives.
And God is always there to listen to you, he is the one who understands you.. More than you yourself! Talk to him and you shall feel much better. Don't loose hope, he is always there when you need him.