In car after Valentine dance, heading to my home for sex. Annoying squeaking in the back of car. I asked him to check it out. Said aggressively NO I would have to check it out. It hurt my feelings. I downplayed it. How should I have handled it?

There are a few things here I need clarified. Heading to your house for sex implies you don't live together, and frankly "to have sex" implies you are not all that emotionally involved. You don't even call him your date, nevertheless a boyfriend. So it doesn't sound like you are all invested in "him" or he in you. So if the squeak is in your car, take it to a mechanic and have it checked out.  If he was driving his own car, not really your business as long as the car is safe. As for him being rude, I would not have had sex. It soundslike he is lacking respect for you.

Pick better sex partners!

Who's car is it? Do you both use it equally regardless of who owns it?

So in a relationship it is not uncommon to "Share responsibilities". Even if one were to divide up the responsibilities a couple has, if a surge in work that demands additional time, might be cause to shift the divided responsibilities to the less "busy" person then you adjust and work through it.  

The first mistake was "Downplaying" how it made you feel. Communicate that it was hurtful to you and reflect upon WHY it was hurtful to you. You want to make sure your expectations aren't unreasonable as well. Some of us guys can be numb to our tones, so please let us know when a response is curt or cutting . . . We may not be thinking through HOW we are answering a question.