I feel so defeated

I'm about ready to kick my 19 year old slacker out of my house. She finally got a job after over a year out of work, makes poor grades, barely helps or clean her own messes, fails to tackle even the tiniest of demands, and is a stoner. I've worked multiple jobs, and worked hard to provide a great life for both of my kids. I've also gone back to school and earned my Bachelors degree this past spring. I've done everything I can to lead by example. No amount of talking or lectures or trying to help has made a difference. It's like she refuses to be an adult. A prime example of this is the car I helped her get a loan on... she failed to pay the first payment on time so I ended up doing it. THEN she crashed it two weeks ago and has yet to complete the process with insurance to have it fixed! (I get furious just thinking about it) Additionally, she has a 14 year old brother who is seeing all of this constant drama/lack of adulting. My kids father lives in another town and has two young step kids (twins, 9 yo). I highly doubt she'd end up there if she left or that she'd be welcomed to take her chaos there. My suspicion is that she'd either end up with a friend or her boyfriend. Where do I draw the line? Also, do I let her keep the car? I feel like I'm drowning! HELP! via /r/Parenting http://ift.tt/2vY9no6