Lipolelo Thabane was shot dead in her car in June 2017 two days before her husband's inauguration. She had reportedly refused him a divorce. He married Maesaiah two months later.
Maesaiah, who is aged 43, has been charged with murder, while Thomas Thabane argued in court in February that he has immunity due to his office. Both deny any wrongdoing.
Thabane's own All Basotho Convention (ABC) party, opposition figures and SA mediators had been leaning on him to quit, but he had resisted, supported by an inner circle of loyalists who wanted him to remain.
Majoro, a former senior IMF official, now faces the task of uniting a fractious political elite in a country that has suffered several coups since independence from Britain in 1966.
Reuters