Hey man, Crusty already set you up with most of the info lol, but i'll go into a bit more detail.
Every Wednesday night @ 7pm, CFAS is at Hard Times Cafe on Sudley Road in Manassas, VA, up on the second floor. $5 Venue Fee +$5 Entry Fee per game/tournament. We have MKX as well as SFV, Smash, and usually a Marvel or Anime set up somewhere too. We usually pack up around midnight, but the restaurant is open until 2 am or so. They also run monthly tournaments 1 Saturday every month.
There's also The Hiero Group (THG) Arena every Monday in Waldorf, MD. Starts at 5 pm at the Thai Palace (right off of 301 in the heart of Waldorf). $5 Venue Fee and the Tournament Fee is Free! Not a huge MKX scene, but if you're into SFV, BlazBlue, or Smash, then hit them up. They also have a stream at Twitch.tv/TheHieroGroup.
Finally, there's also Xanadu Games in Arbutus, MD (south Baltimore). Every Thursday at (im not sure, 7? i dont go to this one a lot, too far for a work day for me). If you google "Xanadu Game Shop Baltimore" it'll be the first thing that pops up. They also run monthly tournaments on Saturdays. The next one is April 16th. For the monthlies it's $10 Venue and $10 per game/tournament (same as CFAS).
There are also numerous, much smaller events all the time, but these are the "Big 3" of the DMV.
If you havent already, I highly suggest you join the "DMV Fighting Game Community" on FaceBook. All of these events, the smaller ones, the players, and the TO's share their stuff on there, and makes finding events super easy.
Let me know if you have any questions breh.