Hey NPO,
Venting is as important as lighting, as important as nutes, as important as odor control, as important as anything else. That said, on my first grow I learned as I went along, too.
Leave the closet door open with a fan blowing in and run it until the temps under the lights at about 75F. If the temperature in the room isn't cool enough to do that, then put an A/C in the window and run it until you have the desired results.
This will handle the venting issue. Now, if you're growing in a place where you can't do that (someone else's house) then you need to get rid of the plant anyway, because you won't be able to control odor. You probably wouldn't be able to do that anyway, so there seem to be several reasons why you might be saying bye-bye to this grow.
Good luck!
EDIT: Hyde's suggestion of switching to cooler lights might be the solution.