It's good to see you back and I'm glad that the rest of your life is looking good even though the difficult child part is still a pain. It's time for you to take a well deserved break from all of the drama. You have nothing to feel badly about because you know that you did your best and tried to help him in any way you could. Some people just don't want to be helped. The old saying is that you can lead a horse to water but you can't make him drink. You provided the water, the tank, the barn, the love, the food, the nurturing, the concern, and everything else you could think of. There is a chance that one day he will realize that. If so, great. If not, you still did the best you could and can be happy about that.
Enjoy your new job. It sounds great, except for the 5:30 part 0 I'm definitely a night owl. About the only time I see 5:30 is if I haven't gone to bed yet!