If it isn't selfish for your father to vent, then it's not selfish for you to vent, either.
No one is stopping you from complaining here. Complain away.
If your family has financial concerns about tuition, you need to take those concerns seriously. If you're footing the bill 100% then what they are saying can be safely ignored. But from what you've written, it doesn't sound like you are paying anything toward tuition.
Ever hear the expression, he who pays the piper calls the tune
If your folks are paying your tuition and they tell you that they can't afford x or y university, then it was foolish to apply to either of them.
Your first two years can be spent at a cheap junior college or community college and then you can transfer. This would be affordable and would show you were acting responsibly.
You are all over the place with this post. In some of it, you're saying you want to be treated like a grownup. Ignoring statements about economic hardship is not the way to go about it.
Bottom line: if you want to be treated like a grownup, then you have got to start acting like one.