Where was her husband?

Irena Krzyżanowska married Mieczysław Sendler in 1931. They divorced in 1947 when, as the film tells us, she then married Stefan Zgrzembski. After their divorce in 1959, she remarried Mieczysław Sendler in 1960. So, obliviously Mieczysław Sendler survived the war. Where was he during the time this film takes place? Does anybody know? I don't remember any mention of him.