Must I return to my husband’s home and apologize to his father and sisters, despite all the insults I endured, or should I seek a divorce, especially since my husband will be leaving within 10 days?

There is no harm in apologizing to the husband's family, even if they are in the wrong. This falls under "repelling [evil] with what is better," in compliance with Allah Almighty's saying: "Repel [evil] with what is better; then suddenly, the one whom between you and him was enmity will become as though he was a devoted friend." And the saying of the Prophet, peace and blessings be upon him, to one who maintains ties with his relatives while they cut him off: "If you are as you say, then it is as if you are feeding them hot ashes, and there will always be a supporter from Allah with you against them as long as you remain upon that." Moreover, this apology resolves the problem and pleases the husband. The marital relationship should be strengthened by focusing on gaining the husband's love, trust, obedience, and sincerity.