Am I sinful for feelings of hatred and isolation from my family because they prevented my marriage, withheld my inheritance, and refused to help me perform Umrah, even though I tried to treat them kindly out of obedience to Allah?

You will not be sinful for the negative feelings you harbor towards your brothers due to their prevention of your marriage, 'Umrah, and inheritance. You are permitted to isolate yourself from them if you fulfill your obligatory devotion to your mother. If a suitable suitor proposes to you for marriage, they have no right to refuse, and your closest guardian should marry you off. If all of them prevent you, then the ruler or his representative should do so. As for inheritance, you should address them gently, and if they insist on preventing you, you are permitted to file a lawsuit to claim your right.