mkwdrs: Hang in there you'll get used to it, with time. A couple of additional tips that may help.
When taking your fare share of the lane give a little signal with your left hand. Usually a simple act of removing your hand from the bar and pointing to the ground towards your left gives the driver behind you an indication you're moving left. I do this whenever I need space or am coming up to a stop light where I have to stop.
Also, to get some more experience out on the road consider doing some organized rides. You can opt for the shorter 15, 25, 25 mile routes until you get more confidence. A lot of the time the first portion of the ride will have police ******* and/or busy intersections blocked off for you.
Finally, if there's no rides near by try to find an area where the road is divided into 4 lanes. Donna and I did this when she first started riding with me. She would ride on my right side close to the curb and I'd ride on the left closer to the other lane. Here in GA you can legally ride side by side so we occupied the right lane and forced drivers to pass us in the left lane. We've done this for quite some time now and not once have we had any problems. Of course it goes without saying that you shouldn't do this during rush hour
Hang in there, it does get better.
Zack