Times will come when adult siblings are in conflict and need to confront and resolve their issues. The reasons for sibling conflict vary, but they often stem from feelings that parents favored one sibling over the other, touching off jealousy and anger. In other cases, one sibling may feel the other is guilty of betrayal, giving rise to difficulty offering forgiveness.
Examine your attitudes. While it's easy to blame your sibling for causing the conflict, it's important to think about the ways you also contributed to the problem. If your sibling accused you of being arrogant and looking down on the rest of the family because they didn't achieve your level of success, then honestly evaluate yourself to see if there is any substance to your sibling's comments. If you are indeed harboring a prideful attitude, assess why. Maybe you feel a sense of shame about your upbringing and feel compelled to impress with success.
Compromise on minor issues. If you have a small disagreement over where your parents will go to live if they're sick, come to a compromise. Don't let weeks pass with the issue remaining unresolved and both of you upset. Maybe allow your parents to stay with your sibling, but invite them to visit you during holidays or summers. This way you both will share parental care responsibilities.
Apologize and forgive. This is especially important because you want to continue building a stable relationship, and years of unforgiveness and anger only hinders this goal. Once you've forgiven each other, don't bring up the offenses repeatedly in future conversations and don't do this in front of others. Resolve not to make the same mistakes again and hold each other accountable to that commitment.