I completely agree that you should get tested. Don't completely freak out as even under the worst of circumstances, the risk is very low for transmission from a one time event. But do test and do use protection from now on!
If this happened less than 72 hours before, get to a doctor and take PEP
Unprotected anal sex carries the highest risk of contracting HIV and yes, you should get tested as soon as possible. This myth that because it only happened once really needs to stop making the rounds! Ask a million or two MOTHERS who got pregnant the night they lost their virginity if there was anything to worry about. They only "did it" once, too. As for asking someone if they are HIV negative, especially someone who does not insist on using a condom, is not a good idea. It's a sad and frightening FACT that people lie.
PLEASE GET TESTED AND ALWAYS, ALWAYS USE PROTECTION.
I wish you the very best outcome.
RubyWitch