When to pull the cord? Parents of ADHD/ Aspie 19 yo need help transitioning him to independence

Everyone in our house is so frustrated and there is no answer in sight.  Just wanted to check in with other parents to see what their approach would be.

Son turns 19 in 3 weeks.  He is Aspie, intellectually above average but not brilliant, very argumentative, very poor memory, no organisational skills and absolutely cannot or will not travel in a straight line.  Generally a good kid and willing worker but has very strong ADD and no impulse control.

Got him through college through endless organisation, research, reviewing work, ensuring completion.  It was literally wall to wall arguments and blood sweat and tears.  This year he is at Tech doing an IT degree majoring in programming which he is a whizz at. 

Decided to ease back this year due to 'He has to grow up and be responsible' and "No-one can live with all this stress and arguing'.  Got him a very basic benefit to help support him . Really only about 60 pounds equivalent but we thought it would give him some independence.  WE still pay everything bar his transport costs and some of his medical.  So phone, tuition, board etc.

Problem number 1, he keeps spending the money on games no matter how many times we tell him not to.  About 300 pounds in 3 months.  He thinks its his money but have explained we are paying for everything and the money is for the odd lunch, travel, books and some other personal expenses like haircuts.

First mini exam of the year and he fails.  No matter how many times we have told him or suggested to him a revision plan and just general organisational habits like looking on google classroom to see if a test is coming up or reading the course outline to find out what and when, he doesn't.  He didn't even put is his exam time extension form despite being asked to maybe 10 times.  He couldn't be bothered filling it out so he didnt.

So I reluctantly intervene and find all the info myself and get on with applying for him to have extra time etc.  And we have come up with  a set of rules around.  Bedtimes, study, gaming times and conditions and behaviour.  He keeps calling me names and arguing about every little thing.

Seem to have semi averted the crisis for now, ie: got him the best chances possible and got him focused on the next few exams.

He doesnt want the rules but we cant live like we are (We cook dinner for him and he wont leave the game long enough to eat it, he wont shower unless made to etc).  And he argues about everything all the time, he is too busy to do housework but, if he does 1 to 2 hours school work, he is entitled to 2 - 3 hours gaming minimum.  Does nothing for himself, makes my husband late for work most mornings as he wont get up off the couch and go and get dressed.

I have told him that if he cant stick to the rules he has to move out.  He says he cant and I am a tyrannical ***hole for giving him rules.  He has no self control.  If I leave him to his own devices he will fail.  He always does because he has no self direction whatsoever.  He wants to succeed but he wont make the effort to succeed.   I also cant be bothered fighting him any more or spending my entire life working for him but I know he wont move out unless I get the police and force him out and I couldnt go that far.

On the other hand, the entire family is tired of him treating us badly, always being so demanding and forcing the rest of us to dance to his tune.  My husband is 65 in 2 months and wants to retire but wont be able to while we are still paying everything for him.   We don't live in the UK and there are no free services for him.  I keep wondering whether he needs a mentor or counselling or whether this is just the way he will always be and that he will never likely move out or even remain home but live independently.  Or whether we just go all tough love on him.  

Suggestions anyone?  Either as parents or as a non neuro typical who has gone through this themselves.

How do we move him towards independence positively?  How much should we and when should we intervene?  As a family, what should we "put up with' and I know that is a horrid thing to say because he does have a disability but the whole family is tired of constant drama.  We love him and we want the best for him but we are not sure what we should do at this stage.

We are trying to get him a license but he isnt particularly motivated to do that.  He will go with us to practice driving but he likes being picked up and dropped off every day.  Its convenient and free.  He wont get his license unless we make it happen.