The fact that his family think it’s you who are after his money would be ringing massive alarm bells for me. I mean, nobody jumps to a conclusion like that without having it suggested to them somehow.
My bet, if I were the gambling type, would be that he’s spinning stories to his sister, that you want money for x y and z, when actually what he wants is money to cover his own gambling habits, and the line he’s spun you about his sisters gambling is just projection. Let’s face it, it would make perfect sense. Your O, ‘can I borrow some money sis? Girlfriend has bought new phone/new shoes/whatever and now I’m short for the mortgage.’ Then he has to pay her back, so he comes to you. ‘Oh love, sis needs some money. She’s run a gambling debt and can’t pay her rent.’ He’s playing you off against each other to cover his own gambling. His family think you’re a frivolous gold digger and you think his sister is a gambling addict, which strangely enough is just what your O happens to be, only he already knows he can push your sympathy buttons with that particular thing, having already done it on his own account. It’s a tried and tested method, only now he’s bullshitting about who the gambler is.
Let me guess, there’s some manufactured reason why you don’t speak to the sister. She thinks you’re a money grabber, O says you can’t mention it because it’s too awkward. There’s some reason why you and sister don’t communicate about what money is changing hands or what it’s supposedly for.
This is not only financially draining, and dangerous, but it’s incredibly deceptive and dishonest.This is not a person you want to be financially bound to. Sooner or later his other sources of money will run dry, and then what? Also, I wouldn’t be so sure that that 30k is the only debt he has. I think there’s an old adage with gamblers, that whatever debts they say they’ve got, double it. There’s always more than they’ll admit to and if he’s still at it, as it would certainly appear he is, then there’s more you don’t know about.
Firstly you need to check he’s got no debts in your name. It’s not beyond the realms of possibility that he has. Secondly you need to sever financial links with him so he can’t drag you down. If you Get a bad credit score due to debt, lose your house or have to sell it you’ll be royally screwed on the credit risk front. That shit can drag you down for years to the point that even getting a mobile contract becomes problematic. You haven’t caused this so you should never have to suffer the consequences. Get smart, or you’ll end up getting shafted.