Lol, you're friends sound a lot like my friends when they "taught" me how to snowboard back in '94. They took me to the top of Stratton and after falling on my face getting off the lift told me, "Ok, now figure out how to get down." 3 hours and many a black and blue later and I was able to falling leaf and link the occasional turn.
In having my wife avoid this issue a few years ago when she decided to switch from skiing to being cool I had her take lessons. I agree with Snowolf in that the group lesson for the real true beginners who don't know any of the basics is definitely the better choice. The value in private lessons is working out the little things you're doing wrong with specialized focus on those areas versus giving the same spiel you'll get in a group beginner lesson. If you do however understand the basics such as getting up, skating etc. then definitely jump to the private if not do the group first.