@Enonymous,
I truly want to comend you for you willingness to help this person. But you have to careful so as to keep things in proper perspective. Although you may not have intended to become close to this young lady and she to you, the fact is men and women cannot interact with each other on this level and an attraction not develop between them.
Your first priority and loyalty is to your wife. No other human relationship should ever be allowed to transcend this relationship. A nice Bible principle that helps in this matter is Titus 1:8 which highlights the quality of being loyal.
Another principal that would also help highlights something that you already fear. That your present situation could compromise your relationship with your wife. Proverbs 22:3 says: "3 The shrewd one sees the danger and conceals himself, But the inexperienced keep right on going and suffer the consequences." Since you see the danger, take steps to direct this young woman to others that can help her.
And finally there is something else you must consider. If this woman you are trying to help truly loves and respects you, then she will not allow herself to act on feelings she knows she has not right to. For her to do so would show disrespect for your wife, and ultimately you since no doubt she knows how much you love your wife.
Help can still be provided to this young lady. But it is obvious that this help cannot come from you. Take the right action my friend and you will be happy in doing so.