If a husband ascertains his wife's infidelity through phone calls and video calls, and his wife is remorseful and declares her repentance, should he divorce her or keep her and accept her repentance? And will he be rewarded for that?

A woman's conversation with non-mahrams without need is a reprehensible act, and its ugliness increases if she is married, because she is obliged to preserve her husband's honor in his absence. If the woman repents and becomes upright, then the husband should forgive her, treat her kindly, and advise her; for one who repents is like one who has no sin.