Willem was one of six children. He grew up in Amsterdam where is parents worked as costume designers. He fought with his parents about his homosexuality.
He left home with no contact with his family. He started writing and painting. In 1932 he moved to the countryside near Apeldoorn.
1933-1939. When Willem was 38, he met Jan Tijssen. They lived together for seven years. He was a struggling painter, but refused to get welfare.
Willem wrote a biography about Matthijs Maris. After the book was published, he was financially doing fine.
1940-1944; In May 1940, the Germans invaded Netherlands. After the occupation, Willem joined the resistance. He had to "falsify identity papers for dutch Jews." Near the end of March 1943, Willem and his unit purposely started a fire at the Amsterdam registry building. Willem and his unit did it to destroy records against false identity papers.