I am on the same side of the tracks as you. My ex-girlfriend gave it to me. At the time I was not interested in proving it was her....... I was in love and going to spend the rest of my life with her. She always said, how in love she was and blah, blah, blah,

. Long story short she dumped me after a vacation

and I decided to do some homework on who I had been with other than my ex-wife. I checked with the one girl, we have always been good friends. She said no questions asked she would go get a full spectrum of test including blood. I saw the results that leaves on person.
I have never confronted her with this information and probably never will. In the big picture it does not matter. I will never really know if she knew she had it or not. By some of things she did, I would bet my bottom dollar on it that she knew.
In the end you have to decide if you love him or not. I loved her so it did not matter to me when she was their. He wants to stay with you, I hope for longer than my ex did with me. It sounds like my ex and your man deserve each other. GOOD LUCK!