dear Heyhey, welcome to the forum, and what is happening is that your partner is only feeding his agony, as his mother pleads for money to purchase smokes or to gamble away, and she knows that she has him right where she wants him, literally under her thumb, and I'm sorry but it's a big mistake.
My wife (ex) and I lent her brother various amounts of money, which I never wanted to do, and this was over a few years amounting to an amount in the high double figures $k to stop him going bankrupt, never got a thank you and of course haven't seen a cent.
I was stupid but was enticed into doing it, it's an expensive lesson to learn, one which I would never allow myself to do.
With your partners mum and her threatening to end her life, can I ask how many times she has said that to him, more than once or twice, and just because she is a gambler and needs smokes to get on with life, I doubt that this would ever happen.
She has to be told on how to manage her money, so much for smokes and so much for the pokies, and when it runs out she will have to wait until her next centrelink payment.
This is where your partner has to come into the equation, and tell her no more, you have too many bills that have to be paid, or you could change your phone number, I know that your partner wouldn't want to do this, but sanity should be first priority.
He shouldn't talk to her on the phone for too long if he still decides to do this, because he's being baited, as she knows what will be his weak points so that he will succumb, maybe you could take the phone off him, and there maybe an argument, so it's now becoming a contentious point.
Your partner I don't think is going to feel at ease either talking to her or not talking to her, so it's a catch-22 situation
L Geoff. x