How do you know he didn't give it to you? Is there a reason you think you had it before?
The only way to know if he has it is for him to take a type specific IgG blood test.
How were you diagnosed? Did they do any type testing? You can take a type specific IgG blood test if they didn't type anything.
It can take up to 12 weeks for the blood tests to become positive, so if this is a new infection, it may not show up yet.
There are two types of herpes - hsv1 is usually oral, like cold sores, but that can be transmitted to the genitals with oral sex. It becomes genital hsv1.
Hsv2 is almost always genital.
They look exactly the same when you get outbreaks, so a doctor can't tell you what type you have when they look at it.
If your doctor didn't culture your tests, and just looked at you and said it's herpes, you should get that confirmed with some testing.
You can go to any of these places and get the test done:
https://www.stdcheck.com/herpes-i-ii-test.php - just choose the hsv1 & II test
https://www.letsgetchecked.com/home-herpes-test/
https://www.healthlabs.com/herpes-tests
https://www.ultalabtests.com/partners/ultdirect/testing/categories/std/herpes
Google coupon codes and just choose the hsv1 and hsv2 tests that are most convenient/cheapest for you.
It does concern me that you haven't yet told your partner. Are you not safe with him? Do you not have open communication?
It's possible that your partner has oral hsv1 and gave you genital hsv1, or you had it before the relationship and didn't know, or your partner did. It's also possible that your partner cheated - this alone isn't enough info for that, though.