@Cacao,
My heart goes out to you. It truly does. I have been in a painfully similar scenario myself. Three years ago a close family member fell victim to end-stage kidney failure at the age of 24. His mother came to me with pleading tears begging me to care for him as she couldn't. So, we moved him into our home and suffered immensely over the course of the following two years. He was abusive, hostile, and suicidal. Having my child in that environment made it all the more stressful. This person and I had been in contention before he ever fell ill as I felt he was rude, explosive, and entitled. He has a history of ill-managed rage and the criminal history to prove it. He manipulates his own family members to the point of heart-break, and assumes I am psycho for standing up for myself. Ultimately, this toll took my mental health as well as my relationship which came to an abrupt end as a result.
That said, I will never encourage you to choose to support someone else at your own expense. There is absolutely no shame in enjoying the reward of a loving home and the well-paying job you have clearly earned. To move back home and hand it all over seems a gross injustice. I understand the desire to help and support your family, but the truth of the matter remains. This is YOUR life, and you are worthy of love and wellness, even if it means severance from your family. I moved clear across the country for a similar reason. While I miss them from time to time, I never think twice about returning myself to a compromised situation where I am abused, unappreciated, and expected to provide income. Please do not feel one ounce of guilt about the life you have built for yourself. Instead, enjoy every single minute of it. Best wishes.