Are you sure you got it from him? The tricky thing about HSV is it can be dormant/asymptomatic for years. On top of that, there's a decent margin of error with blood tests.
Not saying that he may not be gaslighting you, just that it's not always so crystal clear. The only way to be certain of his honesty (or lack thereof) is to see his test results yourself. If he's not willing to provide that, you're probably right about him. However, if he does provide the test results, and they confirm what he is saying, I point you to my earlier statement.