It's unhealthy to self-diagnose, even if friends agree. Only a medical professional can make a diagnoses - both self-assessed and peer evaluations are insufficient to label yourself bipolar.

Anyway on to the matter in hand. It can often be difficult to move on from a past relationship, it should get better with time. I'm not too clued up on what to do if it doesn't eventually begin to be less painful, but talking to a therapist could help. Try and find things to distract yourself.

RB.