Does sincere repentance spare me from Allah's punishment in Barzakh and in the Hereafter, even though I committed many sins and fornication due to harsh circumstances I experienced?

Adultery is a grave indecency, and a husband's ill-treatment does not justify it. A wife who is harmed by such actions has the right to seek divorce. If you have repented and feel remorse, you must engage in abundant supplication for forgiveness (istighfar) and acts of obedience, and keep your matter private, for sincere repentance expiates major sins. Do not despair of Allah's mercy, for Allah accepts the repentance of the sincere. Nevertheless, you should weep over the sin and experience fear and awe of Allah.