Sorry you are struggling, I'm glad you have posted.
3 weeks sounds like a long time to go before speaking to your CPN again given how difficult things seem to be, do you think it would be worth seeing if you could see someone else whilst she is on vacation?
I'm glad that you have emailed a charity, can you hold to meet them tomorrow?
When I am struggling with strong suicidal thoughts I try to write a plan to get through each unit of time that feels achievable whether that is an hour or 5 minutes. Do you think that might help you now?