Am I allowed to stop talking to someone even though they are suicidal?
Why do you think they are suicidal?
He said he was killing himself
You should not abandon a suicidal person without calling for help. You should not have to take the emotional burden on you but should get them help so they don't die.
No point in talking to them if they are going to be dead soon though.
I understand it can be emotionally difficult to deal with someone who is suicidal, but you need to be there for them until they get help. It's inconvenient for you, but you are potentially saving their life.