[harleyquinn]

My opinion:
X has already been given the chance to fess up. His chances are up. He's not a friend, to any of you, and you'd all be better off without him in your life. He's proven how little he thinks of all of you.
Y needs to not worry about X getting in trouble and only about himself. The sooner he goes to the cops and fesses up on his own, the better it'll be for him. The cops will figure it out sooner or later and will also figure out that Y lied to them, and then it'll be too late for Y to do anything about it. However, if Y comes forward, his chances of not being sent off are better. Not to put down your friend, Y, but he made the choice to lie to the police, so as much as it sucks, if he does have consequences to face because of that lie, he only has himself to blame. He should have fessed up to knowing how to get in touch with X in the first place.