I have never written to an advice columnist before. Out of all of the ones I know of, online and off, you are the one I trust the most because of your compassionate and spirited wisdom.
I am a 40-something woman, and I am obsessed with someone who is wrong. This person is someone I know I will never meet, someone who is young enough to be my son, and someone who is accused of an act which is not only extremely stupid but downright murderous.
My logical side (which I personify as Mr. Spock and Mr. Data from "Star Trek") tells me all of the reasons why I should not care one bit about this person: 1) He's too young, 2) We don't have much in common, and 3) I am already married.
I love my husband, I feel I'm lucky to have found him, and I want to protect our marriage. I would never cheat on him with a real person. However, our sex life is nearly nonexistent, perhaps because of age. I have suggested he go to the doctor, but he won't go even for an annual checkup. Until I became obsessed with the young man, my sex drive was not what it used to be, either. Now, it's strong and eager -- and it has no place to go.
Except writing. This new sexual energy has spurred me to write fiction again, and I have started on a book in which the male protagonist is loosely based on the man I'm obsessed with. I don't want to lose this "juice" before I finish this project -- but I don't like the other things the obsession compels me to do, such as endless Google searches about "the subject" and feeling like I'm living in the real world only a quarter of the time. Before this happened, I had an idea for a new business and was actively looking for new places to grow my current career (I work freelance). I also read books of all kinds, liked to explore my community on foot, and was active on social media. Now everything I do (and don't) is coated with this impossible dream.
Inside, I am a tangled mess of erotic fantasy, hopeless woolgathering, and misdirected drive. But sometimes, it feels so delightful.
How can I lose the bad stuff about this and keep the good?
I suggest that whenever these thoughts arise, put them in the book. Do not fight the thoughts. Do not wait impatiently for them to dissipate. Do not put your life off, or walk around in fear of these thoughts. Do not expect to be free of these thoughts. Just put these thoughts into the book.
The things you imagine doing with this man, put them in the book. The conversations you imagine having with him, put them in the book. The conversations you have with yourself about your conversations with him, put them in the book. What you do with yourself while thinking of him, put that in the book.
Who this person is in the real world is an issue. If he is famous, if he has been in the news, then you must decide whether to name him. If your protagonist in the book has this obsession and it makes sense to say who the person is, then it may be permissible and interesting to name him, if he has been in the news. Ask yourself why you are doing this. Is there some intellectual interest in naming the person? Is the person sufficiently well-known that, and are your artistic intentions pure enough that there would not be legal questions of defamation and infringement of publicity rights? And, mainly, what are your artistic intentions?
Intuition says it would be best not to name this person, and to eliminate all physical evidence of his identity. Your artistic intentions may dictate otherwise, but here is what I would suggest: Eliminate all recognizable details of this act he is accused of; change it; put it in a different city; make it a different act; you might even just refer to it obliquely as the act he is accused of.
Put his physical appearance in the book but not in a way that he could be recognized on the street. Actually, it is very hard to describe anyone so he would be recognized on the street unless he has unusual features such as an eye patch or missing limb, or a uniquely shaped scar or tattoo. So that is not a big worry.
Other things not to put in the book: His name and address, do not put that in the book and do not put it on a piece of paper and do not put it in your address book or in your computer.
I also suggest, in order to keep this in the realm of fiction and to maintain control over it: Do not carry with you or have in your house any physical or digital identifying information about this person. Let him exist solely in the realm of fiction. Remove all trace of this man from your actual world until he exists solely in your work of fiction. This is a discipline.
On the other hand: The color of his eyes, how he walks, the hair on his arms, put those things in the book but change them some. Change them into the way you imagine them to be; change them into something a little more intense and a little more strange. Conjure up in your body how these things feel when you imagine them, and put that in the book. Also put all your feelings about him and what it would be like to be with him in the book. But do not say things that sound too intense, like, "Oh, how thrilling to be in his arms." Instead, put in the book the actual, concrete things you imagine doing with him: Where you would go with him, what you would eat, how you would lie down beside him in a railroad station or at the beach.
Try to understand these things you are feeling and what they mean, and put that in the book.
Try and understand why you are having these feelings at this particular time, how it relates to the lack of sex in your marriage, and put that in the book.
Put your feelings about the lack of sex in your marriage into the book. Put into the book the reasons you got married and why you loved your husband and what you were expecting and how that changed. If there is one thing in particular that you were expecting in your marriage that did not happen, put that into the book. Make it clear what that thing was and why you believed it would come true, but do not put in the book actual conversations you had with your husband. Do not put your husband into the book as he actually exists, as he is physically. But put your expectations and feelings into it. For instance, if your decision to marry involved the fanciful wish that after marrying him your life would change in some magical way, put that into the book. But do not put your husband as he actually is. No one needs to know that these are thoughts you actually had. You are giving them to a character.
I say all this because you are telling me that you are a tangled mess and you want to lose the bad stuff about this and keep the good. Writing about it seems a good way to do that -- to examine each piece and see how it fits and how it got that way.
Writing can be good medicine. In your case, it may be the best medicine there is.