used the first needle by accident. Would you recommend PEP?

Last night I had sex sex with an HIV positive and undetectable man. We both used crystal meth by injection into the vain in the arm ("slamming"). I had my second slam about 3 hours after our first one. For the first slam I used the needle first and then he did. I had a second needle and intended to do it the same. However, I used the first needle by accident. I did not wash it after my partner's first slam 3 hours earlier. Am I at risk of catching HIV? Would you recommend PEP? I read about it online and understand that HIV can survive in a needle under certain conditions. Could the undetectable level of HIV have survived in the needle for 3 hours? If so then I will go get PEP immediately. A quick response would be greatly appreciated.