How can I deal with my siblings, whom I blame for not helping me get married despite my urgent and medical need for it, and the worsening of my health and psychological condition due to the delay in marriage?

Marriage is a good thing, and your problem lies in financial capability and choosing a wife.

As for financial capability: your brothers should help you by way of a gift or a loan. If they do not help you, do not supplicate against them.

As for choosing a wife: shyness should not prevent you from searching. You can seek help from your female relatives. With sincere determination and abundant supplication, strive in your search, for marriage is a means to wealth. If marriage is not facilitated, then be patient. If you find no way to ward off harm, and you are distressed and fear for yourself, and fasting does not help, then some scholars have permitted masturbation out of necessity, to the extent of the need.