I'm sorry about the condom break. That's unfortunate. There is, however, extremely low risk. A one time sexual encounter like this is less than 1 percent transmission. I would not be overly worried. You also have the information from her to indicate even less reason to freak out. Yes, you need to get tested. At 28 days or beyond, you can take a 4th generation DUO test and I would expect that to be negative. Pep would not be really indicated in your case as it's reserved for having intercourse with someone known to have hiv. It's a hard medication to take. I think you'll be just fine, man. Try not to worry.
The chances are pretty low. However, you must know that you have exposed your self to risk.
The fact that you were bare inside her for a few seconds is relieving since large quantity of infected fluid exposure is necessary for transmission and don't forget the virus is very fragile. However, you certainly need to test, take a IV/V generation of HIV test at the 28th day from the date of your exposure for a conclusive, if the above stated tests are not accessible take a standard HIV test at or after 6 weeks for a definitive result. I think you should be fine.
She tested neg 3 months ago and always uses condoms. You can't get hiv when you use a condom. Therefore, if you believe her, you had zero risk. You can test conclusively at 4 weeks with a 4 gen test or 3 months with any test, if you want to be sure she isn't lying however I wouldn't worry while waiting.
Your rapid test was a waste of time because of the abovementioned window period and the fact you always used a condom.