In Hindi we have a word- Panoti. It means a person who brings bad luck. Such people in English are referred to as, "Good riddance". It is best to get rid of them ASAP and make your life beautiful.
Such people spread misery, misfortune, bad health, stress, fights, chaos, etc wherever they go.
If you know any such person, run in the opposite direction.
You may do anything for these people but they will be thankless and ungrateful. You may bend backward. But that would not suffice for them. In the end, what you will receive is allegations, accusations, insults, negativity. It is so not worth it.
On the contrary, you will observe that getting rid of them, will make your life smooth, easy and stress free. You will be a better and happier person. You will suddenly have good fortune coming from all sides.
Sometimes we try and try harder. We try to be nicer, more giving and hope against hope to improve things. But sooner you realize that it is so not worth it, to spend your efforts on such people, the better your life will be.
Last but not the least, when you decide to move away and break free of such people, their last resort is insults, insinuations, abuses and finally threats. Pay heed to no such things. Break free and move on.