seriously though, she is an adult now, and probably past going on holiday with her parents. if she wants holidays, she could save up and pay for them herelf, so please don't feel guilty.
i think you feel frustrated at your financial situation, and i can understand that, it's just that it's not your exes fault he earns enough to go on holiday and you don't.
Does the daughter have any contact with her dad? perhaps she can ask him for some mney for a holiday, just as she would have to if he were still living with you