I've been lurking around the TRP for about 5 months now, and have been hitting it pretty hard lately. I'm in the process of unplugging, but need some advice

About 5 months ago I broke up with my 19 y/o girlfriend of 5 years. About a month before that happened she wanted to go to a bed and breakfast for our anniversary. I had no desire to go, but let myself get talked into it. Being a college student I had close to nothing in my bank account, and attempted to use that as an excuse to get out of it, but she offered to pay for the entire thing if paid her back my half. It ended up being about 200$. We broke up before I had a chance to pay her back, so a couple weeks later I told her I still would.

I'm learning to just take it for what it is, but I still have some resentment towards the bitch. A couple weeks after we broke up she fucked one of my friends after spending the weekend at a local school, which drove me up the fucking wall at the time.

She recently texted me saying "You still owe me money. Give to my friend ASAP" The disrespectful tone on top of everything else says that she doesn't deserve the money I owe her, and I don't plan on paying her. Plus 100$ is still quite a bit of money. Am I wrong in thinking this way?

I ignored her for the time being, but I know she's going to keep asking for the money. Opinions and suggestions would be great.