Well, it sounds like you have your work cut out for you.
She needs to be convinced of the value of her soul, the power of bad peers (and error being all around you, especially when it's taught as truth!), etc.
You need to give her a "choice" -- no complaining about lack of friends, or go to St. Mary's. That way, you let her pick her cross -- she can't really complain about it.
My wife does this to me all the time -- when there are two choices, each of which has a major downside, she lets me decide. Then I can't really complain about the downside, since it was my choice.
Tell her you understand her need for friends, even volunteer that man was created by God to be social, but tell her that eating poison is no solution for a starving man. Sometimes nothing is better than something harmful.
You do need to find some solution to this problem of "friends", or she will eventually ditch her Faith to get them. Find some friends online, at Church, or send her to a Catholic school like St. Mary's.
I wish I had a more perfect solution, but there are no neat, tidy, perfect solutions these days.
Matthew