My sibling doesn't have anything to do with my family and when they do, it always end badly. I feel that I am better off not dealing with the sibling and doing everything on my own. But on the other hand, I don't want to have resentment toward my sibling for not helping out. Any advice is greatly appreciated.
Speaking of your brother/sister in the 3rd person ("the sibling"), is an indication you already harbor some ill will. Resentment festers and escalates, and keeping your distance or pretending the person doesn't exist only makes it worse. In a nutshell, attacking/recriminating -- which I assume is the reason why every encounter ends in disaster -- alienates the individual whose help is needed and expected. His/her guard, therefore, will always be up unless the family adopts an amicable tone and approach in order to encourage him/her to share the huge responsibility of caregiving. The individual in question has been trying to pitch in somehow, otherwise s/he wouldn't come over in the first place.
If every time your sibling visits s/he is made to feel less than, I wouldn't be surprised if s/he told you to go to Hades or fell off the map completely. After all, there's only so much abuse a person can take -- whether deserved or not.
Good luck.
-- ED
-- ED