Please help me name this old black and white film.

This is driving me mad, I'll tell you the premise.

A man who has a job as a cashier who has a wife. On his way home he meets a young women who he asks out for coffee. The woman has a scumbag boyfriend. Her boyfriend convinces her to lie to the man so that they can get money, and the man gives her anything she wants. He ends up buying a studio apartment for the woman where the man ends up putting all the paintings. A talent agent comes by and thinks the woman painted them and the man who actually painted them went along with it. She becomes famous, and the man confesses his feelings to her. The woman makes fun of him and he kills her.

This turns his whole life upside down and he loses his job (because he stole money from his work) his wife (because she finds out he had an affair) and goes insane because he pinned the dead on the woman's scumbag boyfriend.

Can someone PLEASE tell me this movie?