I am 20 years old at 17 i dove of a bridge into open water i have a first rib cartilage fracture at the sc joint, what can be done? will it ever heal?

Yes it should: Sterniclavicular injuries are common. At age 17 as u stated this is really a fracture as the medial clavicle growth plate is one of the last to close( usually age 18-21). It's unusual that u are still having pain here 3 years after the initial injury unless u are continuing to 'stress' the joint( bench press, push- ups etc.)almost all of these injuries are treated non-operatively... Gl!