so i just beat fallout 3, i died and all that bullshit...so my question is if i buy the dlc i have to start another char? how do i keep playing with me original char?

Either or!

As someone who hasn't yet played... thanks for ruining the game, ass.

If you buy the DLC, 5 minutes into your game, it should appear, and you can do it.

To keep playing, you have to either wait a few months for the new DLC, or play from pre-entering the Water Purify Room.

If you have DLC, you can play it, but not on your auto-save inside the Water Room.