HOw can you be autonomous if you still need money from your parents? If you need their $$, then they have a right to ask all the questions they want. If you want a life with no one asking questions, go and pay for it yourself. How is this not common sense? My parents made sure this was crystal clear long before I was college age. My brother still lied to them and they made his life very difficult. I told them the truth mostly. My life was MUCH easier and I had a LOT more luxury items. If I didn't want to tell them about something, I often said ti was a matter I really didn't feel comfortable discussing. If I wasn't adult enough to tell my mother this, I probably was not adult enough to be doing it.
This generation of kids thinks they are so adult, but they act like 2 year olds. I hope that in time you will tie some of whatever is important to Ferb to his honesty or to something measurable. He has gotten away with murder and had you providing a fairly cushy life while he did it. I realize you had far bigger things to deal with, but at some point this is going to need to be addressed. Of course if he ends up in jail, it will mean college is off the table. Will you ask him to pay you back for the $$ you spent for the dorm and everything else? My parents would have expected that. It was one of the reasons I never experimented with a lot of things that could get me in big trouble. I couldn't afford to pay them back that much money. This is something to think about and maybe let him know later. I don't know if it will make any difference to him though.
I am glad he is away from that woman's easy influence and grasp, but I am sorry that he is still lying to you so much. Hopefully he will grow up in college and mature quite a bit. If he continues to lie so much, I would have a financial crisis (imagined if it is not real - hope it is not real) and cut the amount of money I was able to send him. Not so much that he was unable to live, but enough that he had to be extra careful and frugal. If he stopped lying to me, I would have a financial reversal. I would not tell him what the crisis was, just that money was super tight and I could not send him as much. He can work as well as go to school to make extra money to help himself out.