Me and my partner lost virginity to each other but I have herpes?

I’ve recently been getting blisters on my vagina and I thought these were due to a yeast infection and my itching but after I used a treatment the sores still haven’t cleared up.

They look like herpes.

I asked my partner if he has slept with anyone else apart from me and he said no, and i haven’t slept with anyone else either.

I’m scared he’s cheated on me and I don’t know what to do.