St. Rita was married to a violent man and their two sons inherited his personality. After eighteen years of marriage, her husband experienced a kind of conversion. Shortly thereafter, he was murdered.
Rita's sons swore vengeance. Concerned for their eternal welfare, Rita prayed that her sons would die rather than commit murder and lose their souls. They did, in fact, fall seriously ill. Their long recovery, through which their doting mother tended to them, gave their anger time to dissipate.
So, no. Although St. Rita clearly valued her sons' eternal destiny more than their temporal welfare, she certainly did not murder them.