I've been re-reading your post keberoxu, and just wanted to add the following:-

Regarding the relative who is 'operatically dropping hints that they can't live with it any more', if these are suicide threats, there are so many agencies they can approach for sympathetic help. Most folk know about the Samaritans for example. And if their despair is due to their situation, they can choose to make changes, move away, become more assertive, get counselling, any number of strategies with which to help themselves.

The person who is using drugs and being physically abusive is particularly someone from whom you need to stay far far away. Their domestic victim/s will probably come to the point where they take protective action. There are various aid agencies who can intervene in domestic violence, including the Police. And I have worked as a volunteer with criminal drug users/addicts, so can say from experience that drug use is extremely difficult to address, and needs the professionals. Even then, the success rates are poor. So you definitely shouldn't even attempt to step in there. Without 'seeing the light' for him/herself, the drug user will almost certainly continue to access drugs, and you will end up exhausted and frustrated.

I feel you've done very well so far in 'saving' yourself and it can't have been easy. It sounds to me as if you may have been a bit of a rescuer in the past, and felt such sympathy and compassion for all these dysfunctional folk that you got sucked in, like a boat in a whirlpool. Now you're paddling strongly in your little canoe towards tranquil waters, and I think you should continue going in that direction. Leave the pirate ship to navigate its own course. If it hits the rocks, it's got nothing to do with you.