This looks like the kind of problem which has happened to me numerous times. From what I can see there is still a fair amount of actual tooth left, so you may very well find that it can be repaired by replacing the filling and shaping the new filling to substitute for the part which broke off. However only a dentist has the experience to make that decision, of course, as he or she will be able to examine the remaining tooth in far more detail. You may also find that an individual dentist will recommend a crown - or not
As for delaying treatment - don't, unless it's an insurmountable financial barrier. Whether or not the tooth hurts is immaterial. You don't want more of it to break off so that you end up in pain and/or needing an extraction. Good luck !