I am wondering why my 2006 e250 superduty is swaying really bad?

The other earlier comments could be correct, but it could also be caused by faulty/failed shock absorbers or a combination of anti-sway bar bushings/links, shock absorbers, or aft center of gravity load distribution, which would take the front load off the front axle. In regards to your comment about play in wheel, with engine off, steering wheel unlocked, grab the steering wheel at twelve o'clock and violently rock it between ten and two o'clock. If you hear clunking, you have worn steering linkage parts. Then have one person rock the wheel while another looks under it to see and touch for the noise source. Also check the pitman arm for looseness. The steering gear may need adjusting. Any of these condition in combination, or all of these conditions are at the root of your linear instability issues.

You may have broke the sway bar free from its mounts. Need to check this out ASAP. The other possibility is you lost one of tie rod ends connected to the steering knuckle.