Chocolate

We have 4 cats and my roommates left out the chocolate brownies and the cats got to it. Our kitten was caught actively eating it but the others were just around. We can barely pay our bills and can’t afford going to a vet. Idk what to do and I have no idea how much the cats ate because I wasn’t the one who left it out and ate some today. I had told them to put it away because our cats try eating food all the time and they know it’s a problem so I’m very upset.

It’s dark chocolate brownies with dark chocolate chips in it. No idea how much or who ate some