I am so sorry too. It was a mistake and mistakes happen unfortunatly. I have experienced both sides.My ex told me about it and we had unprotected sex right before he was having an outbreak I got very upset his excuse was your never sleeping wiht anyone but me anyways and you'll be fine. Well i got it. I was upset and was for a while but eventually i felt better about the situation I should fo protected myself and gotten educated.
On the other hand I have given the virus to my fiancee. Though he was completly aware and was not mad at me because I was honest. I think sometimes thats what upsets people most is not being honest about it.
I would definetly be more open with partners even if that means possible rejection. Try not to beat yourself up too much were all human and your a good person that had a bit of bad judgement I know it was not intentional. As for your ex he may be mad, but eventually he may at least except it. Take care.