That letter sounds as though she is more concerned with herself than for you!

I had a similar issue with a girlfriend (living with me, might as well have been a wife). I used to ride a motorcycle before I met her but didn't own one when I met her and for a couple years after we were together. Then I bought a motorcycle and she freaks out. Her concern was actually completely for my safety (it sound from the letter like your wife's may not be), but in any case you just have to put your foot down on some things and tell her this is the way it's going to be and she's going to have to learn to live with it. I know it's hard and may cause some tension, but the only other choice is having her walk all over you once she figures out she can.