My daughter is going thru mood swings, depressed etc, been to see counsellor but not helped. Please help me.?

She had borderline ovarian cancer 2 years ago and seems to have got worse since then, her mum and I split up, i have a new partner and 2 new children, she has had lots to contend with. She is now saying she wont have any more ops and would rather die. She is not willing to seek any further help. We dont know what else to do and need some advice on what to do next.