I know your question is addressed to Twilight, primarily, but you did ask for others’ responses too.
My reaction to a suicidal threat from anybody, would be to call the GP, or the Mental Health Team, if that person has a history of suicidal attempts, as your mother has.
CGs can be very manipulative and may resort to emotional blackmail in a desperate attempt to get money to gamble.
For a close family member, it would be a terrible legacy to carry if, God forbid, your mother carried out her threat.
My suggestion to you is to inform wider family about the situation you find yourself in. It is a very heavy burden to bear and of course when we weigh up money against a loved one’s life it seems that handing over the money would be the obvious choice.
You need to seek help for YOU , Kevin. Tell your mum, when things are calm that you cannot continue to enable her gambling habit by giving her money. Ask her not to make any further requests of you . Remind her that there is help available and that you will support her when she is ready to reach out for real help.
That is what I would want my son to do.
I am a Mother who is a Compulsive Gambler.
I hope this reply helps.