Hi VL
My son sounds very similar to your son. My difficult child is nearly 20, abusing "just pot" AFAIK and has gone into a downward spiral. He started a good university as a bright honors student, ended his first year with a 2.2 GPA and W in a core class.(which saved his GPA bc he was failing that class)
Readers Digest Version: He came home for summer break. First night home, he was high. We had a huge "to do" which left me emotionally drained and wary. It was not fun having him home all summer. He worked a ton of hours (good) and went out every night (ugh). Although he was not disruptive temperamentally or noticeably altered when he was at home - his entire demeanor had changed. He was barely civil, had a resentful attitude and was not really a part of our family life. We chalked it up to normal growing/empty nest pains and just placated the situation hoping to get him back to school in the fall. We walked on egg shells, when our pleas for him to come home earlier during the work week went unheeded, we just let it be - but we did not enjoy his presence in our home. I think both H and I were trying hard to ignore the *Warning danger ahead* signs blinking over us. He rented an apartment for the upcoming school year without our knowledge and we think he planned to live there on the sly while we paid for his dorm. We placated that as well, even offering to pay the apartment if he could get out of the dorm. He was not very appreciative. A few days before he was due to leave, we found the receipt for a LARGE internet purchase of marijuana paraphernalia being shipped to his new apartment. We sat him down, talked to him asked him to stay home, go to school locally and get help and he refused and left for school without our blessing or financial support. We managed to smooth things over in time for him to come home from the holidays and things were OK on the surface (though we had not paid his tuition etc) He maintained that he had been paying his own way, doing well and wanted to remain independent from us because WE ARE THE PROBLEM and he wanted to control his own life. We later found out that he had dropped out, failed the entire semester, was deeply in debt to the tune of $4500 and had spent all of his savings. He played remorseful because he wanted access to his last & only childhood savings account that I controlled. When I would not liquidate it and give him the CASH, he became menacing, he stormed out and left. I haven't seen nor spoken to him in a month.
Shortly before he came home for holiday break - we went to see him to lay out the guidelines for returning to our home - on the advice of our therapist. Part of our guideline was that he was not able to use our cars so long as we knew he was using substances. Should he want to drive - he needed to provide two blood lab drug tests showing he was substance free, followed up by regular drug testing. That threw the ball back in his court. He chose not to drive. He did not fight us on it because of a local incident that he knows well. (see below)
A local teen was the driver in a fatal car accident last year which killed her bff, and injured her other friend - they were all 17. difficult child knows all 3 girls- all a year younger than he, same HS and he is a close friend of the driver's brother. (fortunately, she hit a median wall & not another innocent vehicle) The dead girl wasn't wearing her seatbelt. None of the girls tested positive for alcohol, but there were liquor bottles in the car (leftover from another night, it was 11:00 am). The driver had trace amounts of marijuana in her system but was not deemed to be driving under the influence. (marijuana stays in the system for 30+ days) These girls were popular but known partiers and had been best friends and inseparable since 6th grade. The parents of the deceased girl pursued heavy punishment. The driver plead guilty (plea bargain) to homicide by negligent use of a vehicle due to the presence of the liquor bottles & trace THC amounts in her bloodstream. She is now a college freshman and convicted felon attending class by day and living in jail (fortunately not prison) when she is not in class. If she tests + for drugs or alcohol, she immediately begins serving a prison sentence for 2-5 years. She and her family are facing multiple (6?) civil lawsuits by both victims/parents and the dead girls parents feel slighted by the short term she is serving. The driver's father's (successful) business is being sued, her parents (divorced) are facing separate law suits, and she is being sued personally as well. It will ruin them financially even if it settles.
When our son first admitted he had failed out of school in January; we came up with a plan for him to live at home and attend community college. He was agreeable at first. Because of the story above, there was no way we would let him drive. I too was not looking forward to taking him to and from school but I was willing to do it under duress. The plan was for him to take classes that were scheduled close together on the same days. I would take him in time for the first class, and he could cool his heels - study, eat etc - at school in between his classes and I would pick him up at the conclusion of his last class. We also encouraged him to find a job he could bike or walk to and from and we (or his younger brother) would drive or pick him up when it wasn't completely inconvenient. It was a sacrifice on our part (especially my own) but I felt I was willing to do so to support him going to school and working.
As far as feeling that your hands are tied. I know how you feel. We had to draw a line in the sand. It broke my heart. But it's become very clear to me that my son is going to continue to use pot regardless of the ill effects it is having on his life and regardless of what his dad and I believe. So the question is - does he live this lifestyle with our financial support or without it? Unfortunately, I unwittingly paid off his debt which enabled him to go back to his apartment. It is very clear to me that I will not financially support his drug use. So we do not. If he wants to go back to school and his grades are good, I will pay his tuition directly to the school. If he wants financial help with his living expenses and his grades are good, we may consider paying his rent directly while he is attending school subject to financial limits. At one point, he was welcome to live at home and go to school locally - but that is no longer on the table due to the way he left a month ago. If the day ever comes where he is desperate and needs somewhere to go - we will assist him with going into rehab. We haven't gone much further because right now he is only interested in being independent and supporting himself so he can party.
I am sorry my answer is so convoluted but I want you to know I have been in your shoes and this is how I am coping. And I hate it - it's a mess and I never thought I would be here. But it is what it is. {{{hugs}}}