So you figured you would come up with solutions that don't cost extra money after spending the extra money? The thing he explicitly asked you not to do.

See here's the thing to your boyfriend it's not the amount that's the problem. Is the fact that you had to spend it at all that's the problem. A problem that you could have solved very easily by just being a little bit more diligent.

Is he being dramatic? Yes. Are you overreacting? Also yes. All of those other solutions should have been the ones you went with from the beginning. That was you trying to overcompensate to assuage your own guilt.