PLEASE HELP! - Is it possible to walk away???

I have come to a point where I am having to make the hardest decision of my life so far. I have recently become close friends with an 11yo girl, S. Over the last few months, I've been mostly at University but whenever I'm home we've seen each other briefly and become special to one another. Over the Christmas holidays we saw a bit more of each other and this last week we arranged to meet up on her route home from school so we could spend some last time together before the start of my new semester. Tuesday's meeting went well and I was on cloud nine for the rest of the day but on Wednesday disaster struck. We bumped straight into a pair of her relatives at the same moment that she had decided to link arms with me. We didn't get them untangled before we were seen. After an uncomfortable silence the rest of the way to her home (accompanied by relatives) we seperated. Thursday I had to go up to her school for unrelated business but I saw S and we spoke briefly. Her mum has told her to keep away from me and I could sense her uncomfortablness. I don't know what else her mum has been saying but it doesn't take a genius to realise that the brainwashing process has begun. That afternoon I had to leave for University, having got no closure on the issue.

Having spoken to a few people last night about what I should do, I am still unsure. Advice has varied from "Walk away and don't look back. There'll be another girl along soon enough" to "Get in there and talk it over with the parents and play a strong Friendship card". I am so confused. I can't even begin to imagine how S must be feeling. I woke up this morning and seriously considered getting straight on a train back home to see her and hopefully find out what I can do. It was only the fact that I was languishing in bed for hours that made it too late to be a serious option by the time I was up.

On top of it all, I have important exams starting on Monday and I cant think about anything but the girl I left behind, least of all revision. I'm going to fail my exams, and S is going to be emotionally scarred for life by her parents and theres nothing I can do.
I have written a first draft of a letter that I am considering sending to S, against my better judgement. Here is what I have so far :

(S),
This is a very hard letter for me to write and I'm still not sure what I hope to achieve by writing it. Things have moved very quickly over the last few days and I want to have an opportunity to set the record straight and set both our minds to rest.
Ideally we would be able to talk in person but me being at University makes that impossible.
Firstly, I think it is now obvious that we can't ever see each other out of Scouting again. Although you and I both know that we did absolutely nothing wrong in our brief time together, I understand that your parents will be concerned about us spending our free time in each others company. This is only natural for them as they think they are doing you a favour by keeping us apart. What they don't understand is that it is not wrong for two people of our ages to want to be friends and that nothing inappropriate did, or ever would, happen between us. This would be okay in itself but I expect that your parents, particularly (S's mum), might try to convince you that I was a bad influence and that you might even come to believe and agree with her given enough time. In particular, it hurts my feelings that they have jumped to a conclusion that I might be dangerous in any way at all. This whole thing is unfair on you and I wouldn't want you to start feeling guilty or angry about the situation. You must understand that none of this was your fault and that sometimes these things just happen to people and theres nothing we can do about it.
Because of this, I dont want you to think I dont want to be friends with you any more. I enjoyed the time we spent together and the little chats we had and I would like to remain good friends with you if that is at all possible. Obviously this will only be through seeing each other occasionally at Scouts whenever I am back in (my home town), but I will say again that it would be nice to hear from you while I am at University, so if you would like to be penpals then please write back to me if you get the chance. I have enclosed a stamped addressed envelope for this purpose.
Much Love,
(Foreverman)
PS. Should any other eyes than (S)'s come to read this letter I sincerely hope they will think hard before making the *right* decision.

Now I have to think long and hard before sending this, or some other draft, to her. If it goes wrong, the parents could do anything from take the letter to the police to fire me from my position in the scout group. However if I dont send it, I'll never know whether the situation could be salvaged and I will have to wait months to see or hear from S, by which time she could be totally turned against me.
Please, I would appreciate anyones thoughts on this! What should I do?

Waiting for the ground to swallow him up,
Foreverman