when he borrowed the money from your mother (used her card)--was there a written contract between them that clearly stated the guidelines for him to repay her and bearing both signatures and that of a notary? If so then your mother has a legal right to take him to court to pursue the repayment. If not, she can still pursue court action, but it would be a matter of word against word and whom the judge decided to believe should your ex choose to deny it being a "loan" and claim it was a "gift" with no expectation of repayment. As to you assisting your mother with the repayment by transferring the balance to yourself - that is an arrangement between you and your mother and not him....so you would have a harder time pursuing it and likely would end up spending more in court costs than you would have a chance of recovering. If you want to make your point then drag his butt to court - but don't expect much satisfaction....that is why it is a rule to ALWAYS put money matters in writing even/especially between family members (even ex family members) and if nothing else at least you will come away from this with a lesson learned (not likely to get much else...)
