should he have to pay me back?

Okay so I was in a serious relationship with this guy for two years. We were in love and talked about gettin married all the time. I really thought he was the one until he dumped me bc he would rather get drunk with his jerk of a best friend. Anyway before he dumped me I asked him to take me to my senior prom. He graduated two years ago, but has gone with me to prom twice already. Anyway, before he dumped me he didn't have the money that day to pay for the third of our prom tickets due that day. So I used my own money and he told me he'd pay me back. He was going to the next day but we both forgot. A week later he asked for a break, then two weeks later officially dumped me. I figured my school would let me combine our tickets so that I would only have to pay for mine. The next payment is due this week and I don't have the money, because my school is still making me pay for both tickets and not just one. So should he have to pay me back? My best friend said he should have too bc he said he would. Plus he should pay for the whole thing just bc of how a jerk he's become. I really thought he was the one too that's what makes this all suck😩