Unhappy and Depressed After Rhinoplasty

This is a serious issue.  At twenty days if is difficult to make valid judgements - too much is in flux.  With that said, major issues may be visable at this point.

Either way - it is not healthy or safe to be that depressed following surgery.  You would be wise to discuss it with your plastic surgeon, your family and friends, and even a mental health care professional -ASAP.

3 weeks is still very early to be evaluating the final results of your rhinoplasty. First off, it's hard to give any general advice without seeing photos. However, as a rule your nose is still swollen three weeks following rhinoplasty. If an external approach was performed, your swelling can actually persist for months. The width in your nasal bridge could be the result of swelling. The "witch like" appearance on the 3/4 view is hard for me to visualize but your nasal tip is likely swollen as well.
Patience is a virtue after rhinoplasty. But if you're concerned, do not suffer in silence. Follow up with your rhinoplasty surgeon. They will know much better than the RealSelf plastic surgeon community what surgical maneuvers were performed and how your nose should look three weeks after their rhinoplasty.
It is not unusual to feel apprehensive and concerned, even depressed, three weeks after facial surgery. Please see your plastic surgeon and discuss your concerns. What you likely need at this point is some reassurance from your doctor and to hear that your doctor is there to support you during the healing process.Stephen Weber MD, FACS

It is entirely too early to have a clear picture of what your nose is going to look like ultimately.  Relax and give it some time for the swelling to subside.  Chances are that nobody out there notices it the way you do.  Get out there and live your life.  You won't really have an idea on the final shape for a few months.  I wouldn't consider a revision for one year as changes can continue to occur.    Good luck and remain calm!