You are 3 weeks post op and any time you stand up your foot swells horribly turns purple w lots of pressure Is this normal?

No, this is not normal and you should contact your doctor immediately. It is possible that you have a blood clot or other serious complication. Swelling, pain, and discoloration are all common signs of a complication after surgery, and you should not hesitate to seek medical attention if you are experiencing these symptoms.