All the children of the woman who breastfed you, from all of her husbands, are brothers and sisters to you

If the situation is as described in the question, and you were breastfed by her for five complete feedings or more within the first two years of your life, then her children from the first husband are your brothers through your father and mother through breastfeeding, and her children from her second husband are your brothers through your mother through breastfeeding only, because Allah said in Soorat al-Nisa’, when mentioning the women who are haraam for marriage (interpretation of the meaning): “Forbidden to you (for marriage) are: your mothers, your daughters”; then He said after that: “your foster mothers who gave you suck, your foster milk suckling sisters” [al-Nisa’ 4:23]. And because the Prophet (blessings and peace of Allah be upon him) said: “What becomes mahram (forbidden for marriage) through breastfeeding is that which becomes mahram through blood ties.” Saheeh – agreed upon. End quote.