Did I fracture my foot or just sprain it. Hard to stand on it due to pain?

Get it checked out. As a general rule: if you didn't feel like standing on it immediately after the injury, then a fracture or severe soft tissue injury is most likely. It is alway better to have it evaluated. Call your doctor for an evaluation. After injury it is usually helpful to follow the rice principle: rest, ice, compression and elevation. Quick treatment will usually improve results and healing. Dr l.
Need examination. If it is hard to stand on the foot, then it is likely that you fractured or tore ligaments enough that it should be evaluated. An x-ray and a short consultation with an orthopedist would put your mind at ease even if there is no fracture or tear.
X-ray. An x-ray can show if there is an underlying fracture. You may have a soft tissue injury if it is just a sprain and may have damaged the muscle, tendon, or ligaments in the area. Have it evaluated by a professional and get the appropriate treatment.