Nos,
If you had this problem in the past, you shouldn't have lent your mother anything. Stand up for yourself! Sounds like you're used to being bullied by your toxic family. I recommend therapy one on one, even if it's just a few visits. In Canada, it's FREE! Get it out, and get yourself away from this destructive behavior once and for all. You're being self-destructive without even knowing it.
As for this, let it go. It's only $25.00, and getting upset and confronting your mother will only make the situation worse for you. Life has so much more waiting for you, and living your life free and happy is the best way to show those toxic to you that they have no control over you. Unfortunately, you are playing right into they're hands by getting upset.
When my toxic family member starts beaking off about other family members, I simply state once and once only that I do not care to discuss things behind people's backs and I don't say things behind they're back that I can't say right to they're face, and that is the end of it. The response is quite shocking, but that's the way that I deal with it. I am in control, and I refuse to listen to nonsense.
Trust me. Your toxic family is driving you crazy, and you can end it right now.