Haven't seen mentioned:
The Ascent (1977)
It's not about ctb from the get go but it leads up to it. Do you choose to live or die. And what are the consequences of that choice. The last scenes are gut wrenching, ends on a note of utter hopelessness and despair. One of my favourites.
Umberto D (1952)
Also not about suicide as a theme but leading up to it. Poverty is a bitch especially if no-one wants to help. It's about an older guy who's about to be kicked out of his appartement. It's kinda melodramatic, so maybe not for everyone. Makes me bawl my eyes out.
Don't want to spoil so I won't say if ctb is succesful in these movies.