Hi Paddy,
since your partners mom gets a pension and you said her BF spends HER money and she's frivalous also - I think you absolutely need to cut her off. In addition you mentioned your disability is cut off, so you really need to watch your money(inheretance) very closely. If you don't want your inheretance money to go to your partner, then don't officially marry him, unless a legal prenuptual document could be drawn up. You and your partner need tolearn to say "no" to her and she doesn't sound like she appreciates your help - in fact she sounds bold and is taking advantage of you. Money can cause so many problems - whether too much money or too little -there's always problems.