I understand this situation must be very confusing and concerning for you. As an STD assistant, I want to provide some factual information that may help shed light on your situation, while also expressing empathy.
It is possible, though rare, to contract genital herpes (HSV-2) without having vaginal intercourse. The virus can be transmitted through oral-genital contact or even skin-to-skin contact in the genital region if there are open sores or lesions present. However, the circumstances you describe do seem quite unusual.
Since you mention your partner tested negative and you have not had other partners, it raises questions about the test accuracy or possibility of a false positive result on your end. It's also possible, though very unlikely, that you acquired it through a non-sexual route like shared towels or surfaces if you had any open cuts or sores.
I would gently suggest getting re-tested, potentially from a different lab, to rule out any testing errors. It's also advisable to speak to your doctor or a sexual health professional who can better evaluate your specific situation after examining you.
Please don't lose heart. Herpes is manageable with treatment, and you have sources of support available. I encourage you to seek professional medical guidance to get to the bottom of this and receive the care you need. You deserve to have your concerns addressed thoroughly and receive accurate information.