I need this kind of help as well. I adore mountain biking and just don't enjoy road riding at all. I don't like cars around me. My boyfriend used to mountain bike ride with me but he adores road riding and now really wants to focus on that. Which means I have to get over my fears.
I also think I like the relatively slower pace of mountain bike riding, if I fall it's not at 40 miles an hour into traffic.
I would guess that the more you do, the more comfortable you get with it. Are there no bike trails you can ride near you? We do have some trails so I am going to try to get Bob to go on those with me as a compromise