If you think you might be affected by this over time, I recommend you keep a distance from her. But if you are confident that it won’t affect you, and that you will be firm in your adherence to proper morality, then you can continue to be friends with her. You can gently bring it up with her and just tell her that you don’t approve of that lifestyle, but you’ll continue to be friends as long as she doesn’t pressure you to be accepting of it.