Emotionally Charged Venter

When a venter is suicidal I usually give them a link to a hotline or a crisis chat online. I tell them that I am not qualified to give them sound advice on their depression but that there are tons of other people who are. Keep talking to them though for a little bit before you disconnect, make sure they seem okay enough to switch over to talk to a different person. If you give them more resources you're still being helpful so I haven't had problems with it.

There's a psychology concept called transferring, where a client transfers his or her feelings about a situation onto the therapist. That being said, you still don't have to take it. The venter may just be upset and not realizing that they are taking it out on you. You can say something like, "I would love to listen to you and be there for you, but it offends me when you speak to me that way."

I would just excuse myself, after the chat takes a personal offence tone, there's no way for me to talk to someone in a composed and detached way. It's also how one should deal with abusive behavior in real life, so better practice it.

For the suicidal venters:
https://blahtherapy.com/faq/ under chat issues