Feelings for my sister In law

I’ve had feelings for my sister in law for a long time. I was hoping over time these feelings would go away but it’s been years and im still struggling with these feelings for her. I love my wife and would never act on it but I can’t understand why I have such strong feelings for her. I don’t see her a lot but when I do I find myself thinking about her more than I should. I’ve never told anyone and really don’t plan to I was hoping just writing it down maybe getting some advice to get rid of these feelings will help.